Add DMA configuration to UART nodes in stm32mp15x (SOC level) and
remove it at board level to keep current PIO behavior when needed.
For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7
(no HW flow control pin available) are kept in PIO mode, while USART3
is now configured in DMA mode.
UART4 (console UART) has to be kept in irq mode, as DMA support for
console has been removed from the driver by commit e359b4411c28 
("serial: stm32: fix threaded interrupt handling"). 

For other stm32mp15x-based boards, current configuration is kept for
all UART instances.

Erwan Le Ray (16):
  ARM: dts: stm32: add DMA configuration to UART nodes on stm32mp151
  ARM: dts: stm32: keep uart4 behavior on stm32mp157c-ed1
  ARM: dts: stm32: keep uart4 and uart7 behavior on stm32mp15xx-dkx
  ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-ctouch2
  ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-edimm2.2
  ARM: dts: stm32: keep uart4 behavior on stm32mp157a-iot-box
  ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0-of7
  ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0
  ARM: dts: stm32: keep uart nodes behavior on stm32mp157a-stinger96
  ARM: dts: stm32: keep uart4 behavior on stm32mp157c-lxa-mc1
  ARM: dts: stm32: keep uart4 behavior on stm32mp157c-odyssey
  ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-drc02
  ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-pdk2
  ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-picoitx
  ARM: dts: stm32: keep uart4 behavior on stm32mp15xx-dhcom-som
  ARM: dts: stm32: keep uart nodes behavior on
    stm32mp15xx-dhcor-avenger96

 arch/arm/boot/dts/stm32mp151.dtsi             | 21 +++++++++++++++++++
 .../stm32mp157a-icore-stm32mp1-ctouch2.dts    |  2 ++
 .../stm32mp157a-icore-stm32mp1-edimm2.2.dts   |  2 ++
 arch/arm/boot/dts/stm32mp157a-iot-box.dts     |  2 ++
 ...157a-microgea-stm32mp1-microdev2.0-of7.dts |  4 ++++
 ...32mp157a-microgea-stm32mp1-microdev2.0.dts |  4 ++++
 arch/arm/boot/dts/stm32mp157a-stinger96.dtsi  |  6 ++++++
 arch/arm/boot/dts/stm32mp157c-ed1.dts         |  2 ++
 arch/arm/boot/dts/stm32mp157c-lxa-mc1.dts     |  2 ++
 arch/arm/boot/dts/stm32mp157c-odyssey.dts     |  2 ++
 .../arm/boot/dts/stm32mp15xx-dhcom-drc02.dtsi |  4 ++++
 arch/arm/boot/dts/stm32mp15xx-dhcom-pdk2.dtsi |  4 ++++
 .../boot/dts/stm32mp15xx-dhcom-picoitx.dtsi   |  4 ++++
 arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi  |  2 ++
 .../boot/dts/stm32mp15xx-dhcor-avenger96.dtsi |  6 ++++++
 arch/arm/boot/dts/stm32mp15xx-dkx.dtsi        |  4 ++++
 16 files changed, 71 insertions(+)

-- 
2.17.1

Hello Erwan,

On 03.02.22 18:10, Erwan Le Ray wrote:
> Add DMA configuration to UART nodes in stm32mp15x (SOC level) and
> remove it at board level to keep current PIO behavior when needed.
> For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7
> (no HW flow control pin available) are kept in PIO mode, while USART3
> is now configured in DMA mode.
> UART4 (console UART) has to be kept in irq mode, as DMA support for
> console has been removed from the driver by commit e359b4411c28 
> ("serial: stm32: fix threaded interrupt handling"). 

Do I understand correctly that your first patch breaks consoles of
most/all boards, because they will briefly use DMA, which is refused
by the stm32-usart driver and then you add a patch for each board
to fix that breakage?

Such intermittent breakage makes bisection a hassle. /delete-property/
is a no-op when the property doesn't exist, so you could move the first
patch to the very end to avoid intermittent breakage.

I also think that the driver's behavior is a bit harsh. I think it would
be better for the UART driver to print a warning and fall back to
PIO for console instead of outright refusing and rendering the system
silent. That's not mutually exclusive with your patch series here, of course.

Cheers,
Ahmad

> 
> For other stm32mp15x-based boards, current configuration is kept for
> all UART instances.
> 
> Erwan Le Ray (16):
>   ARM: dts: stm32: add DMA configuration to UART nodes on stm32mp151
>   ARM: dts: stm32: keep uart4 behavior on stm32mp157c-ed1
>   ARM: dts: stm32: keep uart4 and uart7 behavior on stm32mp15xx-dkx
>   ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-ctouch2
>   ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-edimm2.2
>   ARM: dts: stm32: keep uart4 behavior on stm32mp157a-iot-box
>   ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0-of7
>   ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0
>   ARM: dts: stm32: keep uart nodes behavior on stm32mp157a-stinger96
>   ARM: dts: stm32: keep uart4 behavior on stm32mp157c-lxa-mc1
>   ARM: dts: stm32: keep uart4 behavior on stm32mp157c-odyssey
>   ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-drc02
>   ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-pdk2
>   ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-picoitx
>   ARM: dts: stm32: keep uart4 behavior on stm32mp15xx-dhcom-som
>   ARM: dts: stm32: keep uart nodes behavior on
>     stm32mp15xx-dhcor-avenger96
> 
>  arch/arm/boot/dts/stm32mp151.dtsi             | 21 +++++++++++++++++++
>  .../stm32mp157a-icore-stm32mp1-ctouch2.dts    |  2 ++
>  .../stm32mp157a-icore-stm32mp1-edimm2.2.dts   |  2 ++
>  arch/arm/boot/dts/stm32mp157a-iot-box.dts     |  2 ++
>  ...157a-microgea-stm32mp1-microdev2.0-of7.dts |  4 ++++
>  ...32mp157a-microgea-stm32mp1-microdev2.0.dts |  4 ++++
>  arch/arm/boot/dts/stm32mp157a-stinger96.dtsi  |  6 ++++++
>  arch/arm/boot/dts/stm32mp157c-ed1.dts         |  2 ++
>  arch/arm/boot/dts/stm32mp157c-lxa-mc1.dts     |  2 ++
>  arch/arm/boot/dts/stm32mp157c-odyssey.dts     |  2 ++
>  .../arm/boot/dts/stm32mp15xx-dhcom-drc02.dtsi |  4 ++++
>  arch/arm/boot/dts/stm32mp15xx-dhcom-pdk2.dtsi |  4 ++++
>  .../boot/dts/stm32mp15xx-dhcom-picoitx.dtsi   |  4 ++++
>  arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi  |  2 ++
>  .../boot/dts/stm32mp15xx-dhcor-avenger96.dtsi |  6 ++++++
>  arch/arm/boot/dts/stm32mp15xx-dkx.dtsi        |  4 ++++
>  16 files changed, 71 insertions(+)
> 


-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Hi Ahmad

On 2/3/22 18:25, Ahmad Fatoum wrote:
> Hello Erwan,
> 
> On 03.02.22 18:10, Erwan Le Ray wrote:
>> Add DMA configuration to UART nodes in stm32mp15x (SOC level) and
>> remove it at board level to keep current PIO behavior when needed.
>> For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7
>> (no HW flow control pin available) are kept in PIO mode, while USART3
>> is now configured in DMA mode.
>> UART4 (console UART) has to be kept in irq mode, as DMA support for
>> console has been removed from the driver by commit e359b4411c28
>> ("serial: stm32: fix threaded interrupt handling").
> 
> Do I understand correctly that your first patch breaks consoles of
> most/all boards, because they will briefly use DMA, which is refused
> by the stm32-usart driver and then you add a patch for each board
> to fix that breakage?

We have two solutions and both have pro/drawbacks. The first one (Erwan 
ones, can break the boot if the patch is taken "alone". Your proposition 
avoids this breakage but deletes a non define property (which is a bit 
weird). However I prefer to keep a functional behavior, and keep Ahmad 
proposition. Ahmad, just one question, dt-bindings check doesn't 
complain about it ?

Cheers
Alex

> 
> Such intermittent breakage makes bisection a hassle. /delete-property/
> is a no-op when the property doesn't exist, so you could move the first
> patch to the very end to avoid intermittent breakage.
> 
> I also think that the driver's behavior is a bit harsh. I think it would
> be better for the UART driver to print a warning and fall back to
> PIO for console instead of outright refusing and rendering the system
> silent. That's not mutually exclusive with your patch series here, of course.
> 
> Cheers,
> Ahmad
> 
>>
>> For other stm32mp15x-based boards, current configuration is kept for
>> all UART instances.
>>
>> Erwan Le Ray (16):
>>    ARM: dts: stm32: add DMA configuration to UART nodes on stm32mp151
>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-ed1
>>    ARM: dts: stm32: keep uart4 and uart7 behavior on stm32mp15xx-dkx
>>    ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-ctouch2
>>    ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-edimm2.2
>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157a-iot-box
>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0-of7
>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0
>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp157a-stinger96
>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-lxa-mc1
>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-odyssey
>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-drc02
>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-pdk2
>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-picoitx
>>    ARM: dts: stm32: keep uart4 behavior on stm32mp15xx-dhcom-som
>>    ARM: dts: stm32: keep uart nodes behavior on
>>      stm32mp15xx-dhcor-avenger96
>>
>>   arch/arm/boot/dts/stm32mp151.dtsi             | 21 +++++++++++++++++++
>>   .../stm32mp157a-icore-stm32mp1-ctouch2.dts    |  2 ++
>>   .../stm32mp157a-icore-stm32mp1-edimm2.2.dts   |  2 ++
>>   arch/arm/boot/dts/stm32mp157a-iot-box.dts     |  2 ++
>>   ...157a-microgea-stm32mp1-microdev2.0-of7.dts |  4 ++++
>>   ...32mp157a-microgea-stm32mp1-microdev2.0.dts |  4 ++++
>>   arch/arm/boot/dts/stm32mp157a-stinger96.dtsi  |  6 ++++++
>>   arch/arm/boot/dts/stm32mp157c-ed1.dts         |  2 ++
>>   arch/arm/boot/dts/stm32mp157c-lxa-mc1.dts     |  2 ++
>>   arch/arm/boot/dts/stm32mp157c-odyssey.dts     |  2 ++
>>   .../arm/boot/dts/stm32mp15xx-dhcom-drc02.dtsi |  4 ++++
>>   arch/arm/boot/dts/stm32mp15xx-dhcom-pdk2.dtsi |  4 ++++
>>   .../boot/dts/stm32mp15xx-dhcom-picoitx.dtsi   |  4 ++++
>>   arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi  |  2 ++
>>   .../boot/dts/stm32mp15xx-dhcor-avenger96.dtsi |  6 ++++++
>>   arch/arm/boot/dts/stm32mp15xx-dkx.dtsi        |  4 ++++
>>   16 files changed, 71 insertions(+)
>>
> 
> 

Hi Ahmad,


On 2/4/22 2:22 PM, Alexandre TORGUE wrote:
> Hi Ahmad
> 
> On 2/3/22 18:25, Ahmad Fatoum wrote:
>> Hello Erwan,
>>
>> On 03.02.22 18:10, Erwan Le Ray wrote:
>>> Add DMA configuration to UART nodes in stm32mp15x (SOC level) and
>>> remove it at board level to keep current PIO behavior when needed.
>>> For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7
>>> (no HW flow control pin available) are kept in PIO mode, while USART3
>>> is now configured in DMA mode.
>>> UART4 (console UART) has to be kept in irq mode, as DMA support for
>>> console has been removed from the driver by commit e359b4411c28
>>> ("serial: stm32: fix threaded interrupt handling").
>>
>> Do I understand correctly that your first patch breaks consoles of
>> most/all boards, because they will briefly use DMA, which is refused
>> by the stm32-usart driver and then you add a patch for each board
>> to fix that breakage?
> 
> We have two solutions and both have pro/drawbacks. The first one (Erwan 
> ones, can break the boot if the patch is taken "alone". Your proposition 
> avoids this breakage but deletes a non define property (which is a bit 
> weird). However I prefer to keep a functional behavior, and keep Ahmad 
> proposition. Ahmad, just one question, dt-bindings check doesn't 
> complain about it ?
> 
> Cheers
> Alex
> 
>>
>> Such intermittent breakage makes bisection a hassle. /delete-property/
>> is a no-op when the property doesn't exist, so you could move the first
>> patch to the very end to avoid intermittent breakage.
>>
>> I also think that the driver's behavior is a bit harsh. I think it would
>> be better for the UART driver to print a warning and fall back to
>> PIO for console instead of outright refusing and rendering the system
>> silent. That's not mutually exclusive with your patch series here, of 
>> course.
>>
>> Cheers,
>> Ahmad
>>

The driver implementation will consider the request to probe the UART 
console in DMA mode as an error (-ENODEV), and will fallback this UART 
probe in irq mode.
Whatever the patch ordering, the boot will never be broken. The board dt 
patches aim to get a "proper" implementation, but from functional 
perspective the driver will manage a request to probe an UART console in 
DMA mode as an error and fall it back in irq mode.

Cheers, Erwan.

>>>
>>> For other stm32mp15x-based boards, current configuration is kept for
>>> all UART instances.
>>>
>>> Erwan Le Ray (16):
>>>    ARM: dts: stm32: add DMA configuration to UART nodes on stm32mp151
>>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-ed1
>>>    ARM: dts: stm32: keep uart4 and uart7 behavior on stm32mp15xx-dkx
>>>    ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-ctouch2
>>>    ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-edimm2.2
>>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157a-iot-box
>>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0-of7
>>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0
>>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp157a-stinger96
>>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-lxa-mc1
>>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-odyssey
>>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-drc02
>>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-pdk2
>>>    ARM: dts: stm32: keep uart nodes behavior on 
>>> stm32mp15xx-dhcom-picoitx
>>>    ARM: dts: stm32: keep uart4 behavior on stm32mp15xx-dhcom-som
>>>    ARM: dts: stm32: keep uart nodes behavior on
>>>      stm32mp15xx-dhcor-avenger96
>>>
>>>   arch/arm/boot/dts/stm32mp151.dtsi             | 21 +++++++++++++++++++
>>>   .../stm32mp157a-icore-stm32mp1-ctouch2.dts    |  2 ++
>>>   .../stm32mp157a-icore-stm32mp1-edimm2.2.dts   |  2 ++
>>>   arch/arm/boot/dts/stm32mp157a-iot-box.dts     |  2 ++
>>>   ...157a-microgea-stm32mp1-microdev2.0-of7.dts |  4 ++++
>>>   ...32mp157a-microgea-stm32mp1-microdev2.0.dts |  4 ++++
>>>   arch/arm/boot/dts/stm32mp157a-stinger96.dtsi  |  6 ++++++
>>>   arch/arm/boot/dts/stm32mp157c-ed1.dts         |  2 ++
>>>   arch/arm/boot/dts/stm32mp157c-lxa-mc1.dts     |  2 ++
>>>   arch/arm/boot/dts/stm32mp157c-odyssey.dts     |  2 ++
>>>   .../arm/boot/dts/stm32mp15xx-dhcom-drc02.dtsi |  4 ++++
>>>   arch/arm/boot/dts/stm32mp15xx-dhcom-pdk2.dtsi |  4 ++++
>>>   .../boot/dts/stm32mp15xx-dhcom-picoitx.dtsi   |  4 ++++
>>>   arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi  |  2 ++
>>>   .../boot/dts/stm32mp15xx-dhcor-avenger96.dtsi |  6 ++++++
>>>   arch/arm/boot/dts/stm32mp15xx-dkx.dtsi        |  4 ++++
>>>   16 files changed, 71 insertions(+)
>>>
>>
>>
> 

On Fri, Feb 04, 2022 at 04:41:55PM +0100, Erwan LE RAY wrote:
> On 2/4/22 2:22 PM, Alexandre TORGUE wrote:
> > Hi Ahmad
> > 
> > On 2/3/22 18:25, Ahmad Fatoum wrote:
> > > Hello Erwan,
> > > 
> > > On 03.02.22 18:10, Erwan Le Ray wrote:
> > > > Add DMA configuration to UART nodes in stm32mp15x (SOC level) and
> > > > remove it at board level to keep current PIO behavior when needed.
> > > > For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7
> > > > (no HW flow control pin available) are kept in PIO mode, while USART3
> > > > is now configured in DMA mode.
> > > > UART4 (console UART) has to be kept in irq mode, as DMA support for
> > > > console has been removed from the driver by commit e359b4411c28
> > > > ("serial: stm32: fix threaded interrupt handling").
> > > 
> > > Do I understand correctly that your first patch breaks consoles of
> > > most/all boards, because they will briefly use DMA, which is refused
> > > by the stm32-usart driver and then you add a patch for each board
> > > to fix that breakage?
> > 
> > We have two solutions and both have pro/drawbacks. The first one (Erwan
> > ones, can break the boot if the patch is taken "alone". Your proposition
> > avoids this breakage but deletes a non define property (which is a bit
> > weird). However I prefer to keep a functional behavior, and keep Ahmad
> > proposition. Ahmad, just one question, dt-bindings check doesn't
> > complain about it ?
> > 
> > Cheers
> > Alex
> > 
> > > 
> > > Such intermittent breakage makes bisection a hassle. /delete-property/
> > > is a no-op when the property doesn't exist, so you could move the first
> > > patch to the very end to avoid intermittent breakage.
> > > 
> > > I also think that the driver's behavior is a bit harsh. I think it would
> > > be better for the UART driver to print a warning and fall back to
> > > PIO for console instead of outright refusing and rendering the system
> > > silent. That's not mutually exclusive with your patch series here,
> > > of course.
> > > 
> > > Cheers,
> > > Ahmad
> > > 
> 
> The driver implementation will consider the request to probe the UART
> console in DMA mode as an error (-ENODEV), and will fallback this UART probe
> in irq mode.

> Whatever the patch ordering, the boot will never be broken. The board dt
> patches aim to get a "proper" implementation, but from functional
> perspective the driver will manage a request to probe an UART console in DMA
> mode as an error and fall it back in irq mode.

I didn't debug this further yet, but my machine (with an out-of-tree
dts) fails to boot 6.1-rc4 without removing the dma properties from the
console UART. This is a bug isn't it? The same dts created a working
setup with stm32mp157.dtsi from 5.15 + kernel 5.15.

I can debug this further, but maybe you know off-hand what the problem
is?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

On 11/8/22 12:59, Uwe Kleine-König wrote:
> On Fri, Feb 04, 2022 at 04:41:55PM +0100, Erwan LE RAY wrote:
>> On 2/4/22 2:22 PM, Alexandre TORGUE wrote:
>>> Hi Ahmad
>>>
>>> On 2/3/22 18:25, Ahmad Fatoum wrote:
>>>> Hello Erwan,
>>>>
>>>> On 03.02.22 18:10, Erwan Le Ray wrote:
>>>>> Add DMA configuration to UART nodes in stm32mp15x (SOC level) and
>>>>> remove it at board level to keep current PIO behavior when needed.
>>>>> For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7
>>>>> (no HW flow control pin available) are kept in PIO mode, while USART3
>>>>> is now configured in DMA mode.
>>>>> UART4 (console UART) has to be kept in irq mode, as DMA support for
>>>>> console has been removed from the driver by commit e359b4411c28
>>>>> ("serial: stm32: fix threaded interrupt handling").
>>>>
>>>> Do I understand correctly that your first patch breaks consoles of
>>>> most/all boards, because they will briefly use DMA, which is refused
>>>> by the stm32-usart driver and then you add a patch for each board
>>>> to fix that breakage?
>>>
>>> We have two solutions and both have pro/drawbacks. The first one (Erwan
>>> ones, can break the boot if the patch is taken "alone". Your proposition
>>> avoids this breakage but deletes a non define property (which is a bit
>>> weird). However I prefer to keep a functional behavior, and keep Ahmad
>>> proposition. Ahmad, just one question, dt-bindings check doesn't
>>> complain about it ?
>>>
>>> Cheers
>>> Alex
>>>
>>>>
>>>> Such intermittent breakage makes bisection a hassle. /delete-property/
>>>> is a no-op when the property doesn't exist, so you could move the first
>>>> patch to the very end to avoid intermittent breakage.
>>>>
>>>> I also think that the driver's behavior is a bit harsh. I think it would
>>>> be better for the UART driver to print a warning and fall back to
>>>> PIO for console instead of outright refusing and rendering the system
>>>> silent. That's not mutually exclusive with your patch series here,
>>>> of course.
>>>>
>>>> Cheers,
>>>> Ahmad
>>>>
>>
>> The driver implementation will consider the request to probe the UART
>> console in DMA mode as an error (-ENODEV), and will fallback this UART probe
>> in irq mode.
> 
>> Whatever the patch ordering, the boot will never be broken. The board dt
>> patches aim to get a "proper" implementation, but from functional
>> perspective the driver will manage a request to probe an UART console in DMA
>> mode as an error and fall it back in irq mode.
> 
> I didn't debug this further yet, but my machine (with an out-of-tree
> dts) fails to boot 6.1-rc4 without removing the dma properties from the
> console UART. This is a bug isn't it? The same dts created a working
> setup with stm32mp157.dtsi from 5.15 + kernel 5.15.
> 
> I can debug this further, but maybe you know off-hand what the problem
> is?

+CC Amelie, as this might be related to the DMA series that landed recently:

$ git log --oneline v5.18..v6.0 -- drivers/dma/stm32*

On 11/8/22 16:28, Marek Vasut wrote:
> On 11/8/22 12:59, Uwe Kleine-König wrote:
>> On Fri, Feb 04, 2022 at 04:41:55PM +0100, Erwan LE RAY wrote:
>>> On 2/4/22 2:22 PM, Alexandre TORGUE wrote:
>>>> Hi Ahmad
>>>>
>>>> On 2/3/22 18:25, Ahmad Fatoum wrote:
>>>>> Hello Erwan,
>>>>>
>>>>> On 03.02.22 18:10, Erwan Le Ray wrote:
>>>>>> Add DMA configuration to UART nodes in stm32mp15x (SOC level) and
>>>>>> remove it at board level to keep current PIO behavior when needed.
>>>>>> For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7
>>>>>> (no HW flow control pin available) are kept in PIO mode, while USART3
>>>>>> is now configured in DMA mode.
>>>>>> UART4 (console UART) has to be kept in irq mode, as DMA support for
>>>>>> console has been removed from the driver by commit e359b4411c28
>>>>>> ("serial: stm32: fix threaded interrupt handling").
>>>>>
>>>>> Do I understand correctly that your first patch breaks consoles of
>>>>> most/all boards, because they will briefly use DMA, which is refused
>>>>> by the stm32-usart driver and then you add a patch for each board
>>>>> to fix that breakage?
>>>>
>>>> We have two solutions and both have pro/drawbacks. The first one (Erwan
>>>> ones, can break the boot if the patch is taken "alone". Your 
>>>> proposition
>>>> avoids this breakage but deletes a non define property (which is a bit
>>>> weird). However I prefer to keep a functional behavior, and keep Ahmad
>>>> proposition. Ahmad, just one question, dt-bindings check doesn't
>>>> complain about it ?
>>>>
>>>> Cheers
>>>> Alex
>>>>
>>>>>
>>>>> Such intermittent breakage makes bisection a hassle. /delete-property/
>>>>> is a no-op when the property doesn't exist, so you could move the 
>>>>> first
>>>>> patch to the very end to avoid intermittent breakage.
>>>>>
>>>>> I also think that the driver's behavior is a bit harsh. I think it 
>>>>> would
>>>>> be better for the UART driver to print a warning and fall back to
>>>>> PIO for console instead of outright refusing and rendering the system
>>>>> silent. That's not mutually exclusive with your patch series here,
>>>>> of course.
>>>>>
>>>>> Cheers,
>>>>> Ahmad
>>>>>
>>>
>>> The driver implementation will consider the request to probe the UART
>>> console in DMA mode as an error (-ENODEV), and will fallback this 
>>> UART probe
>>> in irq mode.
>>
>>> Whatever the patch ordering, the boot will never be broken. The board dt
>>> patches aim to get a "proper" implementation, but from functional
>>> perspective the driver will manage a request to probe an UART console 
>>> in DMA
>>> mode as an error and fall it back in irq mode.
>>
>> I didn't debug this further yet, but my machine (with an out-of-tree
>> dts) fails to boot 6.1-rc4 without removing the dma properties from the
>> console UART. This is a bug isn't it? The same dts created a working
>> setup with stm32mp157.dtsi from 5.15 + kernel 5.15.

Hi Uwe,

Could you confirm earlycon is enabled on your setup?

Without earlycon, boot is ok, even with dma properties, at least on 
stm32mp157c-dk2.

>>
>> I can debug this further, but maybe you know off-hand what the problem
>> is?
> 
> +CC Amelie, as this might be related to the DMA series that landed 
> recently:
> 
> $ git log --oneline v5.18..v6.0 -- drivers/dma/stm32*

Hi Marek,

We haven't yet investigated the issue, and if latest DMA updates could 
explain why earlycon breaks the boot.


+TO Valentin, as he's now in charge of UART driver.
Valentin and I will investigate this issue.

Regards,
Amelie

Hi Uwe,

We found the issue, thank you to have reported it.

stm32-usart driver was not tolerant to a probe defer from DMA when the 
earlycon is active.

You can find the patch here:
https://lore.kernel.org/lkml/20221118170602.1057863-1-valentin.caron@foss.st.com/

Valentin

On 11/9/22 14:48, Amelie Delaunay wrote:
> On 11/8/22 16:28, Marek Vasut wrote:
>> On 11/8/22 12:59, Uwe Kleine-König wrote:
>>> On Fri, Feb 04, 2022 at 04:41:55PM +0100, Erwan LE RAY wrote:
>>>> On 2/4/22 2:22 PM, Alexandre TORGUE wrote:
>>>>> Hi Ahmad
>>>>>
>>>>> On 2/3/22 18:25, Ahmad Fatoum wrote:
>>>>>> Hello Erwan,
>>>>>>
>>>>>> On 03.02.22 18:10, Erwan Le Ray wrote:
>>>>>>> Add DMA configuration to UART nodes in stm32mp15x (SOC level) and
>>>>>>> remove it at board level to keep current PIO behavior when needed.
>>>>>>> For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7
>>>>>>> (no HW flow control pin available) are kept in PIO mode, while 
>>>>>>> USART3
>>>>>>> is now configured in DMA mode.
>>>>>>> UART4 (console UART) has to be kept in irq mode, as DMA support for
>>>>>>> console has been removed from the driver by commit e359b4411c28
>>>>>>> ("serial: stm32: fix threaded interrupt handling").
>>>>>>
>>>>>> Do I understand correctly that your first patch breaks consoles of
>>>>>> most/all boards, because they will briefly use DMA, which is refused
>>>>>> by the stm32-usart driver and then you add a patch for each board
>>>>>> to fix that breakage?
>>>>>
>>>>> We have two solutions and both have pro/drawbacks. The first one 
>>>>> (Erwan
>>>>> ones, can break the boot if the patch is taken "alone". Your 
>>>>> proposition
>>>>> avoids this breakage but deletes a non define property (which is a 
>>>>> bit
>>>>> weird). However I prefer to keep a functional behavior, and keep 
>>>>> Ahmad
>>>>> proposition. Ahmad, just one question, dt-bindings check doesn't
>>>>> complain about it ?
>>>>>
>>>>> Cheers
>>>>> Alex
>>>>>
>>>>>>
>>>>>> Such intermittent breakage makes bisection a hassle. 
>>>>>> /delete-property/
>>>>>> is a no-op when the property doesn't exist, so you could move the 
>>>>>> first
>>>>>> patch to the very end to avoid intermittent breakage.
>>>>>>
>>>>>> I also think that the driver's behavior is a bit harsh. I think 
>>>>>> it would
>>>>>> be better for the UART driver to print a warning and fall back to
>>>>>> PIO for console instead of outright refusing and rendering the 
>>>>>> system
>>>>>> silent. That's not mutually exclusive with your patch series here,
>>>>>> of course.
>>>>>>
>>>>>> Cheers,
>>>>>> Ahmad
>>>>>>
>>>>
>>>> The driver implementation will consider the request to probe the UART
>>>> console in DMA mode as an error (-ENODEV), and will fallback this 
>>>> UART probe
>>>> in irq mode.
>>>
>>>> Whatever the patch ordering, the boot will never be broken. The 
>>>> board dt
>>>> patches aim to get a "proper" implementation, but from functional
>>>> perspective the driver will manage a request to probe an UART 
>>>> console in DMA
>>>> mode as an error and fall it back in irq mode.
>>>
>>> I didn't debug this further yet, but my machine (with an out-of-tree
>>> dts) fails to boot 6.1-rc4 without removing the dma properties from the
>>> console UART. This is a bug isn't it? The same dts created a working
>>> setup with stm32mp157.dtsi from 5.15 + kernel 5.15.
>
> Hi Uwe,
>
> Could you confirm earlycon is enabled on your setup?
>
> Without earlycon, boot is ok, even with dma properties, at least on 
> stm32mp157c-dk2.
>
>>>
>>> I can debug this further, but maybe you know off-hand what the problem
>>> is?
>>
>> +CC Amelie, as this might be related to the DMA series that landed 
>> recently:
>>
>> $ git log --oneline v5.18..v6.0 -- drivers/dma/stm32*
>
> Hi Marek,
>
> We haven't yet investigated the issue, and if latest DMA updates could 
> explain why earlycon breaks the boot.
>
>
> +TO Valentin, as he's now in charge of UART driver.
> Valentin and I will investigate this issue.
>
> Regards,
> Amelie

Hello Erwan,

On 04.02.22 16:41, Erwan LE RAY wrote:
> Hi Ahmad,
> 
> 
> On 2/4/22 2:22 PM, Alexandre TORGUE wrote:
>> Hi Ahmad
>>
>> On 2/3/22 18:25, Ahmad Fatoum wrote:
>>> Hello Erwan,
>>>
>>> On 03.02.22 18:10, Erwan Le Ray wrote:
>>>> Add DMA configuration to UART nodes in stm32mp15x (SOC level) and
>>>> remove it at board level to keep current PIO behavior when needed.
>>>> For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7
>>>> (no HW flow control pin available) are kept in PIO mode, while USART3
>>>> is now configured in DMA mode.
>>>> UART4 (console UART) has to be kept in irq mode, as DMA support for
>>>> console has been removed from the driver by commit e359b4411c28
>>>> ("serial: stm32: fix threaded interrupt handling").
>>>
>>> Do I understand correctly that your first patch breaks consoles of
>>> most/all boards, because they will briefly use DMA, which is refused
>>> by the stm32-usart driver and then you add a patch for each board
>>> to fix that breakage?
>>
>> We have two solutions and both have pro/drawbacks. The first one (Erwan ones, can break the boot if the patch is taken "alone". Your proposition avoids this breakage but deletes a non define property (which is a bit weird). However I prefer to keep a functional behavior, and keep Ahmad proposition. Ahmad, just one question, dt-bindings check doesn't complain about it ?
>>
>> Cheers
>> Alex
>>
>>>
>>> Such intermittent breakage makes bisection a hassle. /delete-property/
>>> is a no-op when the property doesn't exist, so you could move the first
>>> patch to the very end to avoid intermittent breakage.
>>>
>>> I also think that the driver's behavior is a bit harsh. I think it would
>>> be better for the UART driver to print a warning and fall back to
>>> PIO for console instead of outright refusing and rendering the system
>>> silent. That's not mutually exclusive with your patch series here, of course.
>>>
>>> Cheers,
>>> Ahmad
>>>
> 
> The driver implementation will consider the request to probe the UART console in DMA mode as an error (-ENODEV), and will fallback this UART probe in irq mode.
> Whatever the patch ordering, the boot will never be broken. The board dt patches aim to get a "proper" implementation, but from functional perspective the driver will manage a request to probe an UART console in DMA mode as an error and fall it back in irq mode.

Thanks for the clarification. In that case, your changes look good to me.

Cheers,
Ahmad

> 
> Cheers, Erwan.
> 
>>>>
>>>> For other stm32mp15x-based boards, current configuration is kept for
>>>> all UART instances.
>>>>
>>>> Erwan Le Ray (16):
>>>>    ARM: dts: stm32: add DMA configuration to UART nodes on stm32mp151
>>>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-ed1
>>>>    ARM: dts: stm32: keep uart4 and uart7 behavior on stm32mp15xx-dkx
>>>>    ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-ctouch2
>>>>    ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-edimm2.2
>>>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157a-iot-box
>>>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0-of7
>>>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0
>>>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp157a-stinger96
>>>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-lxa-mc1
>>>>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-odyssey
>>>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-drc02
>>>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-pdk2
>>>>    ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-picoitx
>>>>    ARM: dts: stm32: keep uart4 behavior on stm32mp15xx-dhcom-som
>>>>    ARM: dts: stm32: keep uart nodes behavior on
>>>>      stm32mp15xx-dhcor-avenger96
>>>>
>>>>   arch/arm/boot/dts/stm32mp151.dtsi             | 21 +++++++++++++++++++
>>>>   .../stm32mp157a-icore-stm32mp1-ctouch2.dts    |  2 ++
>>>>   .../stm32mp157a-icore-stm32mp1-edimm2.2.dts   |  2 ++
>>>>   arch/arm/boot/dts/stm32mp157a-iot-box.dts     |  2 ++
>>>>   ...157a-microgea-stm32mp1-microdev2.0-of7.dts |  4 ++++
>>>>   ...32mp157a-microgea-stm32mp1-microdev2.0.dts |  4 ++++
>>>>   arch/arm/boot/dts/stm32mp157a-stinger96.dtsi  |  6 ++++++
>>>>   arch/arm/boot/dts/stm32mp157c-ed1.dts         |  2 ++
>>>>   arch/arm/boot/dts/stm32mp157c-lxa-mc1.dts     |  2 ++
>>>>   arch/arm/boot/dts/stm32mp157c-odyssey.dts     |  2 ++
>>>>   .../arm/boot/dts/stm32mp15xx-dhcom-drc02.dtsi |  4 ++++
>>>>   arch/arm/boot/dts/stm32mp15xx-dhcom-pdk2.dtsi |  4 ++++
>>>>   .../boot/dts/stm32mp15xx-dhcom-picoitx.dtsi   |  4 ++++
>>>>   arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi  |  2 ++
>>>>   .../boot/dts/stm32mp15xx-dhcor-avenger96.dtsi |  6 ++++++
>>>>   arch/arm/boot/dts/stm32mp15xx-dkx.dtsi        |  4 ++++
>>>>   16 files changed, 71 insertions(+)
>>>>
>>>
>>>
>>
> 


-- 
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Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

On 2/3/22 18:10, Erwan Le Ray wrote:
> Add DMA configuration to UART nodes in stm32mp15x (SOC level) and
> remove it at board level to keep current PIO behavior when needed.
> For stm32-ed1 and stm32-dkx boards, UART4 (console) and UART7
> (no HW flow control pin available) are kept in PIO mode, while USART3
> is now configured in DMA mode.
> UART4 (console UART) has to be kept in irq mode, as DMA support for
> console has been removed from the driver by commit e359b4411c28
> ("serial: stm32: fix threaded interrupt handling").
> 
> For other stm32mp15x-based boards, current configuration is kept for
> all UART instances.
> 
> Erwan Le Ray (16):
>    ARM: dts: stm32: add DMA configuration to UART nodes on stm32mp151
>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-ed1
>    ARM: dts: stm32: keep uart4 and uart7 behavior on stm32mp15xx-dkx
>    ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-ctouch2
>    ARM: dts: stm32: keep uart4 behavior on icore-stm32mp1-edimm2.2
>    ARM: dts: stm32: keep uart4 behavior on stm32mp157a-iot-box
>    ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0-of7
>    ARM: dts: stm32: keep uart nodes behavior on stm32mp1-microdev2.0
>    ARM: dts: stm32: keep uart nodes behavior on stm32mp157a-stinger96
>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-lxa-mc1
>    ARM: dts: stm32: keep uart4 behavior on stm32mp157c-odyssey
>    ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-drc02
>    ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-pdk2
>    ARM: dts: stm32: keep uart nodes behavior on stm32mp15xx-dhcom-picoitx
>    ARM: dts: stm32: keep uart4 behavior on stm32mp15xx-dhcom-som
>    ARM: dts: stm32: keep uart nodes behavior on
>      stm32mp15xx-dhcor-avenger96
> 
>   arch/arm/boot/dts/stm32mp151.dtsi             | 21 +++++++++++++++++++
>   .../stm32mp157a-icore-stm32mp1-ctouch2.dts    |  2 ++
>   .../stm32mp157a-icore-stm32mp1-edimm2.2.dts   |  2 ++
>   arch/arm/boot/dts/stm32mp157a-iot-box.dts     |  2 ++
>   ...157a-microgea-stm32mp1-microdev2.0-of7.dts |  4 ++++
>   ...32mp157a-microgea-stm32mp1-microdev2.0.dts |  4 ++++
>   arch/arm/boot/dts/stm32mp157a-stinger96.dtsi  |  6 ++++++
>   arch/arm/boot/dts/stm32mp157c-ed1.dts         |  2 ++
>   arch/arm/boot/dts/stm32mp157c-lxa-mc1.dts     |  2 ++
>   arch/arm/boot/dts/stm32mp157c-odyssey.dts     |  2 ++
>   .../arm/boot/dts/stm32mp15xx-dhcom-drc02.dtsi |  4 ++++
>   arch/arm/boot/dts/stm32mp15xx-dhcom-pdk2.dtsi |  4 ++++
>   .../boot/dts/stm32mp15xx-dhcom-picoitx.dtsi   |  4 ++++
>   arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi  |  2 ++
>   .../boot/dts/stm32mp15xx-dhcor-avenger96.dtsi |  6 ++++++
>   arch/arm/boot/dts/stm32mp15xx-dkx.dtsi        |  4 ++++
>   16 files changed, 71 insertions(+)
> 
Series applied on stm32-next.

Thanks
Alex