[v3] serial: 8250: Apply FSL workarounds also without SERIAL_8250_CONSOLE

[PATCH v3 2/2] serial: 8250: Apply FSL workarounds also without SERIAL_8250_CONSOLE

Posted by Uwe Kleine-König 2 years, 8 months ago

The need to handle the FSL variant of 8250 in a special way is also
present without console support. So soften the dependency for
SERIAL_8250_FSL accordingly. Note that with the 8250 driver compiled as
a module, some devices still might not make use of the needed
workarounds. That affects the ports instantiated in
arch/powerpc/kernel/legacy_serial.c.

This issue was identified by Dominik Andreas Schorpp.

To cope for CONFIG_SERIAL_8250=m + CONFIG_SERIAL_8250_FSL=y, 8250_fsl.o
must be put in the same compilation unit as 8250_port.o because the
latter defines some functions needed in the former and so 8250_fsl.o
must not be built-in if 8250_port.o is available in a module.

Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230531083230.2702181-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/tty/serial/8250/Kconfig  | 2 +-
 drivers/tty/serial/8250/Makefile | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 5313aa31930f..10c09b19c871 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -378,7 +378,7 @@ config SERIAL_8250_BCM2835AUX
 
 config SERIAL_8250_FSL
 	bool "Freescale 16550 UART support" if COMPILE_TEST && !(PPC || ARM || ARM64)
-	depends on SERIAL_8250_CONSOLE
+	depends on SERIAL_8250
 	default PPC || ARM || ARM64
 	help
 	  Selecting this option enables a workaround for a break-detection
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 4fc2fc1f41b6..8824ba5295b6 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_SERIAL_8250)		+= 8250.o 8250_base.o
 8250_base-$(CONFIG_SERIAL_8250_DMA)	+= 8250_dma.o
 8250_base-$(CONFIG_SERIAL_8250_DWLIB)	+= 8250_dwlib.o
 8250_base-$(CONFIG_SERIAL_8250_FINTEK)	+= 8250_fintek.o
+8250_base-$(CONFIG_SERIAL_8250_FSL)	+= 8250_fsl.o
 8250_base-$(CONFIG_SERIAL_8250_PCILIB)	+= 8250_pcilib.o
 obj-$(CONFIG_SERIAL_8250_PARISC)	+= 8250_parisc.o
 obj-$(CONFIG_SERIAL_8250_PCI)		+= 8250_pci.o
@@ -28,7 +29,6 @@ obj-$(CONFIG_SERIAL_8250_BOCA)		+= 8250_boca.o
 obj-$(CONFIG_SERIAL_8250_EXAR_ST16C554)	+= 8250_exar_st16c554.o
 obj-$(CONFIG_SERIAL_8250_HUB6)		+= 8250_hub6.o
 obj-$(CONFIG_SERIAL_8250_PCI1XXXX)	+= 8250_pci1xxxx.o
-obj-$(CONFIG_SERIAL_8250_FSL)		+= 8250_fsl.o
 obj-$(CONFIG_SERIAL_8250_MEN_MCB)	+= 8250_men_mcb.o
 obj-$(CONFIG_SERIAL_8250_DFL)		+= 8250_dfl.o
 obj-$(CONFIG_SERIAL_8250_DW)		+= 8250_dw.o
-- 
2.39.2

Re: [PATCH v3 2/2] serial: 8250: Apply FSL workarounds also without SERIAL_8250_CONSOLE

Posted by Ilpo Järvinen 2 years, 8 months ago

On Mon, 5 Jun 2023, Uwe Kleine-König wrote:

> The need to handle the FSL variant of 8250 in a special way is also
> present without console support. So soften the dependency for
> SERIAL_8250_FSL accordingly. Note that with the 8250 driver compiled as
> a module, some devices still might not make use of the needed
> workarounds. That affects the ports instantiated in
> arch/powerpc/kernel/legacy_serial.c.
> 
> This issue was identified by Dominik Andreas Schorpp.
> 
> To cope for CONFIG_SERIAL_8250=m + CONFIG_SERIAL_8250_FSL=y, 8250_fsl.o
> must be put in the same compilation unit as 8250_port.o because the
> latter defines some functions needed in the former and so 8250_fsl.o
> must not be built-in if 8250_port.o is available in a module.
> 
> Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> Link: https://lore.kernel.org/r/20230531083230.2702181-1-u.kleine-koenig@pengutronix.de
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  drivers/tty/serial/8250/Kconfig  | 2 +-
>  drivers/tty/serial/8250/Makefile | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
> index 5313aa31930f..10c09b19c871 100644
> --- a/drivers/tty/serial/8250/Kconfig
> +++ b/drivers/tty/serial/8250/Kconfig
> @@ -378,7 +378,7 @@ config SERIAL_8250_BCM2835AUX
>  
>  config SERIAL_8250_FSL
>  	bool "Freescale 16550 UART support" if COMPILE_TEST && !(PPC || ARM || ARM64)
> -	depends on SERIAL_8250_CONSOLE
> +	depends on SERIAL_8250

Just one additional thought: After the adding the arch side 
workaround/hack, SERIAL_8250_FSL could become a tristate?

(1/2 might need a small change to take into account that it can now be a 
module).

>  	default PPC || ARM || ARM64
>  	help
>  	  Selecting this option enables a workaround for a break-detection
> diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
> index 4fc2fc1f41b6..8824ba5295b6 100644
> --- a/drivers/tty/serial/8250/Makefile
> +++ b/drivers/tty/serial/8250/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_SERIAL_8250)		+= 8250.o 8250_base.o
>  8250_base-$(CONFIG_SERIAL_8250_DMA)	+= 8250_dma.o
>  8250_base-$(CONFIG_SERIAL_8250_DWLIB)	+= 8250_dwlib.o
>  8250_base-$(CONFIG_SERIAL_8250_FINTEK)	+= 8250_fintek.o
> +8250_base-$(CONFIG_SERIAL_8250_FSL)	+= 8250_fsl.o
>  8250_base-$(CONFIG_SERIAL_8250_PCILIB)	+= 8250_pcilib.o
>  obj-$(CONFIG_SERIAL_8250_PARISC)	+= 8250_parisc.o
>  obj-$(CONFIG_SERIAL_8250_PCI)		+= 8250_pci.o
> @@ -28,7 +29,6 @@ obj-$(CONFIG_SERIAL_8250_BOCA)		+= 8250_boca.o
>  obj-$(CONFIG_SERIAL_8250_EXAR_ST16C554)	+= 8250_exar_st16c554.o
>  obj-$(CONFIG_SERIAL_8250_HUB6)		+= 8250_hub6.o
>  obj-$(CONFIG_SERIAL_8250_PCI1XXXX)	+= 8250_pci1xxxx.o
> -obj-$(CONFIG_SERIAL_8250_FSL)		+= 8250_fsl.o
>  obj-$(CONFIG_SERIAL_8250_MEN_MCB)	+= 8250_men_mcb.o
>  obj-$(CONFIG_SERIAL_8250_DFL)		+= 8250_dfl.o
>  obj-$(CONFIG_SERIAL_8250_DW)		+= 8250_dw.o

-- 
 i.

Re: [PATCH v3 2/2] serial: 8250: Apply FSL workarounds also without SERIAL_8250_CONSOLE

Posted by Uwe Kleine-König 2 years, 8 months ago

On Mon, Jun 05, 2023 at 04:22:55PM +0300, Ilpo Järvinen wrote:
> On Mon, 5 Jun 2023, Uwe Kleine-König wrote:
> 
> > The need to handle the FSL variant of 8250 in a special way is also
> > present without console support. So soften the dependency for
> > SERIAL_8250_FSL accordingly. Note that with the 8250 driver compiled as
> > a module, some devices still might not make use of the needed
> > workarounds. That affects the ports instantiated in
> > arch/powerpc/kernel/legacy_serial.c.
> > 
> > This issue was identified by Dominik Andreas Schorpp.
> > 
> > To cope for CONFIG_SERIAL_8250=m + CONFIG_SERIAL_8250_FSL=y, 8250_fsl.o
> > must be put in the same compilation unit as 8250_port.o because the
> > latter defines some functions needed in the former and so 8250_fsl.o
> > must not be built-in if 8250_port.o is available in a module.
> > 
> > Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> > Link: https://lore.kernel.org/r/20230531083230.2702181-1-u.kleine-koenig@pengutronix.de
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > ---
> >  drivers/tty/serial/8250/Kconfig  | 2 +-
> >  drivers/tty/serial/8250/Makefile | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
> > index 5313aa31930f..10c09b19c871 100644
> > --- a/drivers/tty/serial/8250/Kconfig
> > +++ b/drivers/tty/serial/8250/Kconfig
> > @@ -378,7 +378,7 @@ config SERIAL_8250_BCM2835AUX
> >  
> >  config SERIAL_8250_FSL
> >  	bool "Freescale 16550 UART support" if COMPILE_TEST && !(PPC || ARM || ARM64)
> > -	depends on SERIAL_8250_CONSOLE
> > +	depends on SERIAL_8250
> 
> Just one additional thought: After the adding the arch side 
> workaround/hack, SERIAL_8250_FSL could become a tristate?

I see no benefit for a module separate from 8250_base.ko. There are
dependencies in both directions between 8250_port.o and 8250_fsl.o[1].
So in my book a bool SERIAL_8250_FSL that modifies 8250_base.ko (with
SERIAL_8250=m) is fine.

Best regards
Uwe

[1] 8250_port.o uses fsl8250_handle_irq() from 8250_fsl.o, and
8250_fsl.o uses serial8250_modem_status from 8250_port.o.

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

Re: [PATCH v3 2/2] serial: 8250: Apply FSL workarounds also without SERIAL_8250_CONSOLE

Posted by Ilpo Järvinen 2 years, 8 months ago

On Mon, 5 Jun 2023, Uwe Kleine-König wrote:

> On Mon, Jun 05, 2023 at 04:22:55PM +0300, Ilpo Järvinen wrote:
> > On Mon, 5 Jun 2023, Uwe Kleine-König wrote:
> > 
> > > The need to handle the FSL variant of 8250 in a special way is also
> > > present without console support. So soften the dependency for
> > > SERIAL_8250_FSL accordingly. Note that with the 8250 driver compiled as
> > > a module, some devices still might not make use of the needed
> > > workarounds. That affects the ports instantiated in
> > > arch/powerpc/kernel/legacy_serial.c.
> > > 
> > > This issue was identified by Dominik Andreas Schorpp.
> > > 
> > > To cope for CONFIG_SERIAL_8250=m + CONFIG_SERIAL_8250_FSL=y, 8250_fsl.o
> > > must be put in the same compilation unit as 8250_port.o because the
> > > latter defines some functions needed in the former and so 8250_fsl.o
> > > must not be built-in if 8250_port.o is available in a module.
> > > 
> > > Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> > > Link: https://lore.kernel.org/r/20230531083230.2702181-1-u.kleine-koenig@pengutronix.de
> > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > > ---
> > >  drivers/tty/serial/8250/Kconfig  | 2 +-
> > >  drivers/tty/serial/8250/Makefile | 2 +-
> > >  2 files changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
> > > index 5313aa31930f..10c09b19c871 100644
> > > --- a/drivers/tty/serial/8250/Kconfig
> > > +++ b/drivers/tty/serial/8250/Kconfig
> > > @@ -378,7 +378,7 @@ config SERIAL_8250_BCM2835AUX
> > >  
> > >  config SERIAL_8250_FSL
> > >  	bool "Freescale 16550 UART support" if COMPILE_TEST && !(PPC || ARM || ARM64)
> > > -	depends on SERIAL_8250_CONSOLE
> > > +	depends on SERIAL_8250
> > 
> > Just one additional thought: After the adding the arch side 
> > workaround/hack, SERIAL_8250_FSL could become a tristate?
> 
> I see no benefit for a module separate from 8250_base.ko. There are
> dependencies in both directions between 8250_port.o and 8250_fsl.o[1].
> So in my book a bool SERIAL_8250_FSL that modifies 8250_base.ko (with
> SERIAL_8250=m) is fine.
> 
> Best regards
> Uwe
> 
> [1] 8250_port.o uses fsl8250_handle_irq() from 8250_fsl.o

Is that after some fix which isn't in tty-next? I see only these:

$ git grep -l fsl8250_handle_irq
arch/powerpc/kernel/legacy_serial.c
drivers/tty/serial/8250/8250_fsl.c
drivers/tty/serial/8250/8250_of.c
include/linux/serial_8250.h

No users of fsl8250_handle_irq in 8250_port.c.

-- 
 i.

>, and 8250_fsl.o uses serial8250_modem_status from 8250_port.o.

Re: [PATCH v3 2/2] serial: 8250: Apply FSL workarounds also without SERIAL_8250_CONSOLE

Posted by Uwe Kleine-König 2 years, 8 months ago

Hello Ilpo,

On Mon, Jun 05, 2023 at 04:44:08PM +0300, Ilpo Järvinen wrote:
> On Mon, 5 Jun 2023, Uwe Kleine-König wrote:
> > On Mon, Jun 05, 2023 at 04:22:55PM +0300, Ilpo Järvinen wrote:
> > > On Mon, 5 Jun 2023, Uwe Kleine-König wrote:
> > > 
> > > > The need to handle the FSL variant of 8250 in a special way is also
> > > > present without console support. So soften the dependency for
> > > > SERIAL_8250_FSL accordingly. Note that with the 8250 driver compiled as
> > > > a module, some devices still might not make use of the needed
> > > > workarounds. That affects the ports instantiated in
> > > > arch/powerpc/kernel/legacy_serial.c.
> > > > 
> > > > This issue was identified by Dominik Andreas Schorpp.
> > > > 
> > > > To cope for CONFIG_SERIAL_8250=m + CONFIG_SERIAL_8250_FSL=y, 8250_fsl.o
> > > > must be put in the same compilation unit as 8250_port.o because the
> > > > latter defines some functions needed in the former and so 8250_fsl.o
> > > > must not be built-in if 8250_port.o is available in a module.
> > > > 
> > > > Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> > > > Link: https://lore.kernel.org/r/20230531083230.2702181-1-u.kleine-koenig@pengutronix.de
> > > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > > > ---
> > > >  drivers/tty/serial/8250/Kconfig  | 2 +-
> > > >  drivers/tty/serial/8250/Makefile | 2 +-
> > > >  2 files changed, 2 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
> > > > index 5313aa31930f..10c09b19c871 100644
> > > > --- a/drivers/tty/serial/8250/Kconfig
> > > > +++ b/drivers/tty/serial/8250/Kconfig
> > > > @@ -378,7 +378,7 @@ config SERIAL_8250_BCM2835AUX
> > > >  
> > > >  config SERIAL_8250_FSL
> > > >  	bool "Freescale 16550 UART support" if COMPILE_TEST && !(PPC || ARM || ARM64)
> > > > -	depends on SERIAL_8250_CONSOLE
> > > > +	depends on SERIAL_8250
> > > 
> > > Just one additional thought: After the adding the arch side 
> > > workaround/hack, SERIAL_8250_FSL could become a tristate?
> > 
> > I see no benefit for a module separate from 8250_base.ko. There are
> > dependencies in both directions between 8250_port.o and 8250_fsl.o[1].
> > So in my book a bool SERIAL_8250_FSL that modifies 8250_base.ko (with
> > SERIAL_8250=m) is fine.
> > 
> > Best regards
> > Uwe
> > 
> > [1] 8250_port.o uses fsl8250_handle_irq() from 8250_fsl.o
> 
> Is that after some fix which isn't in tty-next? I see only these:
> 
> $ git grep -l fsl8250_handle_irq
> arch/powerpc/kernel/legacy_serial.c
> drivers/tty/serial/8250/8250_fsl.c
> drivers/tty/serial/8250/8250_of.c
> include/linux/serial_8250.h
> 
> No users of fsl8250_handle_irq in 8250_port.c.

Ah right, I was too quick:

	8250_of.o uses fsl8250_handle_irq() from 8250_fsl.o
	8250_fsl.o uses serial8250_modem_status() from 8250_port.o (which is in 8250_base.o)


However linking 8250_fsl.o in 8250_of.o isn't a good solution either as
8250_fsl.o should also be available with CONFIG_SERIAL_OF_PLATFORM
disabled to provide the ACPI driver. And as 8250_of.o already depends on
8250_port.o (e.g. via serial8250_em485_config()) adding 8250_fsl.o
together with 8250_port.o into 8250_base.ko is fine and doesn't add new
dependencies.

Best regards
Uwe

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

Re: [PATCH v3 2/2] serial: 8250: Apply FSL workarounds also without SERIAL_8250_CONSOLE

Posted by Ilpo Järvinen 2 years, 8 months ago

On Mon, 5 Jun 2023, Uwe Kleine-König wrote:

> Hello Ilpo,
> 
> On Mon, Jun 05, 2023 at 04:44:08PM +0300, Ilpo Järvinen wrote:
> > On Mon, 5 Jun 2023, Uwe Kleine-König wrote:
> > > On Mon, Jun 05, 2023 at 04:22:55PM +0300, Ilpo Järvinen wrote:
> > > > On Mon, 5 Jun 2023, Uwe Kleine-König wrote:
> > > > 
> > > > > The need to handle the FSL variant of 8250 in a special way is also
> > > > > present without console support. So soften the dependency for
> > > > > SERIAL_8250_FSL accordingly. Note that with the 8250 driver compiled as
> > > > > a module, some devices still might not make use of the needed
> > > > > workarounds. That affects the ports instantiated in
> > > > > arch/powerpc/kernel/legacy_serial.c.
> > > > > 
> > > > > This issue was identified by Dominik Andreas Schorpp.
> > > > > 
> > > > > To cope for CONFIG_SERIAL_8250=m + CONFIG_SERIAL_8250_FSL=y, 8250_fsl.o
> > > > > must be put in the same compilation unit as 8250_port.o because the
> > > > > latter defines some functions needed in the former and so 8250_fsl.o
> > > > > must not be built-in if 8250_port.o is available in a module.
> > > > > 
> > > > > Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> > > > > Link: https://lore.kernel.org/r/20230531083230.2702181-1-u.kleine-koenig@pengutronix.de
> > > > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > > > > ---
> > > > >  drivers/tty/serial/8250/Kconfig  | 2 +-
> > > > >  drivers/tty/serial/8250/Makefile | 2 +-
> > > > >  2 files changed, 2 insertions(+), 2 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
> > > > > index 5313aa31930f..10c09b19c871 100644
> > > > > --- a/drivers/tty/serial/8250/Kconfig
> > > > > +++ b/drivers/tty/serial/8250/Kconfig
> > > > > @@ -378,7 +378,7 @@ config SERIAL_8250_BCM2835AUX
> > > > >  
> > > > >  config SERIAL_8250_FSL
> > > > >  	bool "Freescale 16550 UART support" if COMPILE_TEST && !(PPC || ARM || ARM64)
> > > > > -	depends on SERIAL_8250_CONSOLE
> > > > > +	depends on SERIAL_8250
> > > > 
> > > > Just one additional thought: After the adding the arch side 
> > > > workaround/hack, SERIAL_8250_FSL could become a tristate?
> > > 
> > > I see no benefit for a module separate from 8250_base.ko. There are
> > > dependencies in both directions between 8250_port.o and 8250_fsl.o[1].
> > > So in my book a bool SERIAL_8250_FSL that modifies 8250_base.ko (with
> > > SERIAL_8250=m) is fine.
> > > 
> > > Best regards
> > > Uwe
> > > 
> > > [1] 8250_port.o uses fsl8250_handle_irq() from 8250_fsl.o
> > 
> > Is that after some fix which isn't in tty-next? I see only these:
> > 
> > $ git grep -l fsl8250_handle_irq
> > arch/powerpc/kernel/legacy_serial.c
> > drivers/tty/serial/8250/8250_fsl.c
> > drivers/tty/serial/8250/8250_of.c
> > include/linux/serial_8250.h
> > 
> > No users of fsl8250_handle_irq in 8250_port.c.
> 
> Ah right, I was too quick:
> 
> 	8250_of.o uses fsl8250_handle_irq() from 8250_fsl.o
> 	8250_fsl.o uses serial8250_modem_status() from 8250_port.o (which is in 8250_base.o)
> 
> 
> However linking 8250_fsl.o in 8250_of.o isn't a good solution either as
> 8250_fsl.o should also be available with CONFIG_SERIAL_OF_PLATFORM
> disabled to provide the ACPI driver. And as 8250_of.o already depends on
> 8250_port.o (e.g. via serial8250_em485_config()) adding 8250_fsl.o
> together with 8250_port.o into 8250_base.ko is fine and doesn't add new
> dependencies.

So we have dependencies one-way only:

8250_port

/\    |\
        \
8250_fsl \
         /
/\      /

8250_of

There's no loop here, both they be indepedent modules and configured 
independently (with a correct IS_*() in 8250_of.c).

-- 
 i.

Re: [PATCH v3 2/2] serial: 8250: Apply FSL workarounds also without SERIAL_8250_CONSOLE

Posted by Andy Shevchenko 2 years, 8 months ago

On Mon, Jun 05, 2023 at 04:44:08PM +0300, Ilpo Järvinen wrote:
> On Mon, 5 Jun 2023, Uwe Kleine-König wrote:
> > On Mon, Jun 05, 2023 at 04:22:55PM +0300, Ilpo Järvinen wrote:
> > > On Mon, 5 Jun 2023, Uwe Kleine-König wrote:
> > > > The need to handle the FSL variant of 8250 in a special way is also
> > > > present without console support. So soften the dependency for
> > > > SERIAL_8250_FSL accordingly. Note that with the 8250 driver compiled as
> > > > a module, some devices still might not make use of the needed
> > > > workarounds. That affects the ports instantiated in
> > > > arch/powerpc/kernel/legacy_serial.c.
> > > > 
> > > > This issue was identified by Dominik Andreas Schorpp.
> > > > 
> > > > To cope for CONFIG_SERIAL_8250=m + CONFIG_SERIAL_8250_FSL=y, 8250_fsl.o
> > > > must be put in the same compilation unit as 8250_port.o because the
> > > > latter defines some functions needed in the former and so 8250_fsl.o
> > > > must not be built-in if 8250_port.o is available in a module.
> > > > 
> > > > Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> > > > Link: https://lore.kernel.org/r/20230531083230.2702181-1-u.kleine-koenig@pengutronix.de
> > > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > > > ---
> > > >  drivers/tty/serial/8250/Kconfig  | 2 +-
> > > >  drivers/tty/serial/8250/Makefile | 2 +-
> > > >  2 files changed, 2 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
> > > > index 5313aa31930f..10c09b19c871 100644
> > > > --- a/drivers/tty/serial/8250/Kconfig
> > > > +++ b/drivers/tty/serial/8250/Kconfig
> > > > @@ -378,7 +378,7 @@ config SERIAL_8250_BCM2835AUX
> > > >  
> > > >  config SERIAL_8250_FSL
> > > >  	bool "Freescale 16550 UART support" if COMPILE_TEST && !(PPC || ARM || ARM64)
> > > > -	depends on SERIAL_8250_CONSOLE
> > > > +	depends on SERIAL_8250
> > > 
> > > Just one additional thought: After the adding the arch side 
> > > workaround/hack, SERIAL_8250_FSL could become a tristate?
> > 
> > I see no benefit for a module separate from 8250_base.ko. There are
> > dependencies in both directions between 8250_port.o and 8250_fsl.o[1].
> > So in my book a bool SERIAL_8250_FSL that modifies 8250_base.ko (with
> > SERIAL_8250=m) is fine.

> > [1] 8250_port.o uses fsl8250_handle_irq() from 8250_fsl.o
> 
> Is that after some fix which isn't in tty-next? I see only these:
> 
> $ git grep -l fsl8250_handle_irq
> arch/powerpc/kernel/legacy_serial.c
> drivers/tty/serial/8250/8250_fsl.c
> drivers/tty/serial/8250/8250_of.c
> include/linux/serial_8250.h
> 
> No users of fsl8250_handle_irq in 8250_port.c.

> >, and 8250_fsl.o uses serial8250_modem_status from 8250_port.o.

I don't like 8250_base to be fattened by some stuff that has no
generic meaning. Can we avoid putting every quirk there?

-- 
With Best Regards,
Andy Shevchenko