The SM6350 doesn't have MST support, as such it is not compatible with
the SM8350 platform. Add new entry for SM6350 with fallback to SC7180
(which belongs to the same generation and also doesn't have MST
support).
Fixes: 39086151593a ("dt-bindings: display: msm: dp-controller: document SM6350 compatible")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
---
.../devicetree/bindings/display/msm/dp-controller.yaml | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
index aed3bafa67e3c24d2a876acd29660378b367603a..0f814aa6f51406fdbdd7386027f88dfbacb24392 100644
--- a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
+++ b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
@@ -31,13 +31,25 @@ properties:
- qcom,sm8650-dp
- items:
- enum:
- - qcom,sar2130p-dp
- qcom,sm6350-dp
+ - const: qcom,sc7180-dp
+
+ # deprecated entry for compatibility with old DT
+ - items:
+ - enum:
+ - qcom,sm6350-dp
+ - const: qcom,sm8350-dp
+ deprecated: true
+
+ - items:
+ - enum:
+ - qcom,sar2130p-dp
- qcom,sm8150-dp
- qcom,sm8250-dp
- qcom,sm8450-dp
- qcom,sm8550-dp
- const: qcom,sm8350-dp
+
- items:
- enum:
- qcom,sm8750-dp
--
2.47.2On Fri, Aug 29, 2025 at 01:48:15AM +0300, Dmitry Baryshkov wrote:
> The SM6350 doesn't have MST support, as such it is not compatible with
> the SM8350 platform. Add new entry for SM6350 with fallback to SC7180
> (which belongs to the same generation and also doesn't have MST
> support).
>
> Fixes: 39086151593a ("dt-bindings: display: msm: dp-controller: document SM6350 compatible")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> ---
> .../devicetree/bindings/display/msm/dp-controller.yaml | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> index aed3bafa67e3c24d2a876acd29660378b367603a..0f814aa6f51406fdbdd7386027f88dfbacb24392 100644
> --- a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> +++ b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> @@ -31,13 +31,25 @@ properties:
> - qcom,sm8650-dp
> - items:
> - enum:
> - - qcom,sar2130p-dp
> - qcom,sm6350-dp
> + - const: qcom,sc7180-dp
> +
> + # deprecated entry for compatibility with old DT
> + - items:
> + - enum:
> + - qcom,sm6350-dp
> + - const: qcom,sm8350-dp
> + deprecated: true
If it is only about bindings then there is little benefit in keeping
this, just drop this case. However you cannot drop it from DTS, so this
is a bit pointless.
Lack of MST support is not informative enough to claim it is not
compatible with 8350. For example if it was working fine via fallback,
then that statement is simply not correct.
And it HAD to work fine, because there is nothing binding to
qcom,sm6350-dp.
Best regards,
Krzysztof
On Mon, Sep 01, 2025 at 05:45:49AM +0200, Krzysztof Kozlowski wrote:
> On Fri, Aug 29, 2025 at 01:48:15AM +0300, Dmitry Baryshkov wrote:
> > The SM6350 doesn't have MST support, as such it is not compatible with
> > the SM8350 platform. Add new entry for SM6350 with fallback to SC7180
> > (which belongs to the same generation and also doesn't have MST
> > support).
> >
> > Fixes: 39086151593a ("dt-bindings: display: msm: dp-controller: document SM6350 compatible")
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> > ---
> > .../devicetree/bindings/display/msm/dp-controller.yaml | 14 +++++++++++++-
> > 1 file changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> > index aed3bafa67e3c24d2a876acd29660378b367603a..0f814aa6f51406fdbdd7386027f88dfbacb24392 100644
> > --- a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> > +++ b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> > @@ -31,13 +31,25 @@ properties:
> > - qcom,sm8650-dp
> > - items:
> > - enum:
> > - - qcom,sar2130p-dp
> > - qcom,sm6350-dp
> > + - const: qcom,sc7180-dp
> > +
> > + # deprecated entry for compatibility with old DT
> > + - items:
> > + - enum:
> > + - qcom,sm6350-dp
> > + - const: qcom,sm8350-dp
> > + deprecated: true
>
> If it is only about bindings then there is little benefit in keeping
> this, just drop this case. However you cannot drop it from DTS, so this
> is a bit pointless.
Our plan is:
- land updated DT bindings, describing MST clocks on MST-enabled
platforms,
- land updated DTS, adding MST clocks where applicable,
- land driver changes, keeping legacy support for non-MST DTs on
MST-enabled SoCs
>
> Lack of MST support is not informative enough to claim it is not
> compatible with 8350. For example if it was working fine via fallback,
> then that statement is simply not correct.
>
> And it HAD to work fine, because there is nothing binding to
> qcom,sm6350-dp.
It is working fine since currently we don't have MST support on the
driver side (nor do we describe MST clocks in DT). It's true that the
driver will have to handle non-MST DT for SM8350. However I definitely
don't want to describe both cases in the bindings. SM6350 is not going
to be compatible with the MST-enabled SM8350 schema.
Yes, it's again a lesson of 'describe hardware from the beginning', the
same issue as we observe with several other Qualcomm cores.
--
With best wishes
Dmitry
On 02/09/2025 06:03, Dmitry Baryshkov wrote:
> On Mon, Sep 01, 2025 at 05:45:49AM +0200, Krzysztof Kozlowski wrote:
>> On Fri, Aug 29, 2025 at 01:48:15AM +0300, Dmitry Baryshkov wrote:
>>> The SM6350 doesn't have MST support, as such it is not compatible with
>>> the SM8350 platform. Add new entry for SM6350 with fallback to SC7180
>>> (which belongs to the same generation and also doesn't have MST
>>> support).
>>>
>>> Fixes: 39086151593a ("dt-bindings: display: msm: dp-controller: document SM6350 compatible")
>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
>>> ---
>>> .../devicetree/bindings/display/msm/dp-controller.yaml | 14 +++++++++++++-
>>> 1 file changed, 13 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
>>> index aed3bafa67e3c24d2a876acd29660378b367603a..0f814aa6f51406fdbdd7386027f88dfbacb24392 100644
>>> --- a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
>>> +++ b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
>>> @@ -31,13 +31,25 @@ properties:
>>> - qcom,sm8650-dp
>>> - items:
>>> - enum:
>>> - - qcom,sar2130p-dp
>>> - qcom,sm6350-dp
>>> + - const: qcom,sc7180-dp
>>> +
>>> + # deprecated entry for compatibility with old DT
>>> + - items:
>>> + - enum:
>>> + - qcom,sm6350-dp
>>> + - const: qcom,sm8350-dp
>>> + deprecated: true
>>
>> If it is only about bindings then there is little benefit in keeping
>> this, just drop this case. However you cannot drop it from DTS, so this
>> is a bit pointless.
>
> Our plan is:
> - land updated DT bindings, describing MST clocks on MST-enabled
> platforms,
> - land updated DTS, adding MST clocks where applicable,
This part breaks all out-of-tree users of DTS.
> - land driver changes, keeping legacy support for non-MST DTs on
> MST-enabled SoCs
>
>>
>> Lack of MST support is not informative enough to claim it is not
>> compatible with 8350. For example if it was working fine via fallback,
>> then that statement is simply not correct.
>>
>> And it HAD to work fine, because there is nothing binding to
>> qcom,sm6350-dp.
>
> It is working fine since currently we don't have MST support on the
> driver side (nor do we describe MST clocks in DT). It's true that the
> driver will have to handle non-MST DT for SM8350. However I definitely
> don't want to describe both cases in the bindings. SM6350 is not going
> to be compatible with the MST-enabled SM8350 schema.
The question is rather: is SM6350 going to be compatible (working) with
MST-enabled drivers.
Best regards,
Krzysztof
On Tue, Sep 02, 2025 at 08:04:54AM +0200, Krzysztof Kozlowski wrote:
> On 02/09/2025 06:03, Dmitry Baryshkov wrote:
> > On Mon, Sep 01, 2025 at 05:45:49AM +0200, Krzysztof Kozlowski wrote:
> >> On Fri, Aug 29, 2025 at 01:48:15AM +0300, Dmitry Baryshkov wrote:
> >>> The SM6350 doesn't have MST support, as such it is not compatible with
> >>> the SM8350 platform. Add new entry for SM6350 with fallback to SC7180
> >>> (which belongs to the same generation and also doesn't have MST
> >>> support).
> >>>
> >>> Fixes: 39086151593a ("dt-bindings: display: msm: dp-controller: document SM6350 compatible")
> >>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> >>> ---
> >>> .../devicetree/bindings/display/msm/dp-controller.yaml | 14 +++++++++++++-
> >>> 1 file changed, 13 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> >>> index aed3bafa67e3c24d2a876acd29660378b367603a..0f814aa6f51406fdbdd7386027f88dfbacb24392 100644
> >>> --- a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> >>> +++ b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> >>> @@ -31,13 +31,25 @@ properties:
> >>> - qcom,sm8650-dp
> >>> - items:
> >>> - enum:
> >>> - - qcom,sar2130p-dp
> >>> - qcom,sm6350-dp
> >>> + - const: qcom,sc7180-dp
> >>> +
> >>> + # deprecated entry for compatibility with old DT
> >>> + - items:
> >>> + - enum:
> >>> + - qcom,sm6350-dp
> >>> + - const: qcom,sm8350-dp
> >>> + deprecated: true
> >>
> >> If it is only about bindings then there is little benefit in keeping
> >> this, just drop this case. However you cannot drop it from DTS, so this
> >> is a bit pointless.
> >
> > Our plan is:
> > - land updated DT bindings, describing MST clocks on MST-enabled
> > platforms,
> > - land updated DTS, adding MST clocks where applicable,
>
> This part breaks all out-of-tree users of DTS.
User of which one? SM6350 or all DTS?
It extends the ABI, so no, it shouldn't. We add regions and clocks,
existing users can use the previously defined feature set.
Anyway, is it about adding more explicit note to the cover letter and/or
commit message or would you have any other proposal on how to handle the
issue?
>
> > - land driver changes, keeping legacy support for non-MST DTs on
> > MST-enabled SoCs
> >
> >>
> >> Lack of MST support is not informative enough to claim it is not
> >> compatible with 8350. For example if it was working fine via fallback,
> >> then that statement is simply not correct.
> >>
> >> And it HAD to work fine, because there is nothing binding to
> >> qcom,sm6350-dp.
> >
> > It is working fine since currently we don't have MST support on the
> > driver side (nor do we describe MST clocks in DT). It's true that the
> > driver will have to handle non-MST DT for SM8350. However I definitely
> > don't want to describe both cases in the bindings. SM6350 is not going
> > to be compatible with the MST-enabled SM8350 schema.
>
> The question is rather: is SM6350 going to be compatible (working) with
> MST-enabled drivers.
If somebody implements e.g. U-Boot DP MST support after we land DP MST
bindings, I would not guarantee that. SM8350 will already have second
stream clock.
--
With best wishes
Dmitry
On 02/09/2025 12:01, Dmitry Baryshkov wrote:
> On Tue, Sep 02, 2025 at 08:04:54AM +0200, Krzysztof Kozlowski wrote:
>> On 02/09/2025 06:03, Dmitry Baryshkov wrote:
>>> On Mon, Sep 01, 2025 at 05:45:49AM +0200, Krzysztof Kozlowski wrote:
>>>> On Fri, Aug 29, 2025 at 01:48:15AM +0300, Dmitry Baryshkov wrote:
>>>>> The SM6350 doesn't have MST support, as such it is not compatible with
>>>>> the SM8350 platform. Add new entry for SM6350 with fallback to SC7180
>>>>> (which belongs to the same generation and also doesn't have MST
>>>>> support).
>>>>>
>>>>> Fixes: 39086151593a ("dt-bindings: display: msm: dp-controller: document SM6350 compatible")
>>>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
>>>>> ---
>>>>> .../devicetree/bindings/display/msm/dp-controller.yaml | 14 +++++++++++++-
>>>>> 1 file changed, 13 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
>>>>> index aed3bafa67e3c24d2a876acd29660378b367603a..0f814aa6f51406fdbdd7386027f88dfbacb24392 100644
>>>>> --- a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
>>>>> +++ b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
>>>>> @@ -31,13 +31,25 @@ properties:
>>>>> - qcom,sm8650-dp
>>>>> - items:
>>>>> - enum:
>>>>> - - qcom,sar2130p-dp
>>>>> - qcom,sm6350-dp
>>>>> + - const: qcom,sc7180-dp
>>>>> +
>>>>> + # deprecated entry for compatibility with old DT
>>>>> + - items:
>>>>> + - enum:
>>>>> + - qcom,sm6350-dp
>>>>> + - const: qcom,sm8350-dp
>>>>> + deprecated: true
>>>>
>>>> If it is only about bindings then there is little benefit in keeping
>>>> this, just drop this case. However you cannot drop it from DTS, so this
>>>> is a bit pointless.
>>>
>>> Our plan is:
>>> - land updated DT bindings, describing MST clocks on MST-enabled
>>> platforms,
>>> - land updated DTS, adding MST clocks where applicable,
>>
>> This part breaks all out-of-tree users of DTS.
>
> User of which one? SM6350 or all DTS?
SM6350.
>
> It extends the ABI, so no, it shouldn't. We add regions and clocks,
No, it does not extend the ABI. You are changing the fallback, so you
are changing the ABI.
> existing users can use the previously defined feature set.
>
> Anyway, is it about adding more explicit note to the cover letter and/or
> commit message or would you have any other proposal on how to handle the
> issue?
Please be explicit if Linux was working with the old fallback or not. In
the DTS change be explicit about impact, e.g. that sc7180 fallback is
there since forever.
>
>>
>>> - land driver changes, keeping legacy support for non-MST DTs on
>>> MST-enabled SoCs
>>>
>>>>
>>>> Lack of MST support is not informative enough to claim it is not
>>>> compatible with 8350. For example if it was working fine via fallback,
>>>> then that statement is simply not correct.
>>>>
>>>> And it HAD to work fine, because there is nothing binding to
>>>> qcom,sm6350-dp.
>>>
>>> It is working fine since currently we don't have MST support on the
>>> driver side (nor do we describe MST clocks in DT). It's true that the
>>> driver will have to handle non-MST DT for SM8350. However I definitely
>>> don't want to describe both cases in the bindings. SM6350 is not going
>>> to be compatible with the MST-enabled SM8350 schema.
>>
>> The question is rather: is SM6350 going to be compatible (working) with
>> MST-enabled drivers.
>
> If somebody implements e.g. U-Boot DP MST support after we land DP MST
> bindings, I would not guarantee that. SM8350 will already have second
> stream clock.
Having second stream clock does not mean device stops working with Linux
kernel. I can easily imagine both cases after adding MST to the drivers,
the SM6350 stops working or keeps working...
Best regards,
Krzysztof
On Tue, Sep 02, 2025 at 02:09:02PM +0200, Krzysztof Kozlowski wrote:
> On 02/09/2025 12:01, Dmitry Baryshkov wrote:
> > On Tue, Sep 02, 2025 at 08:04:54AM +0200, Krzysztof Kozlowski wrote:
> >> On 02/09/2025 06:03, Dmitry Baryshkov wrote:
> >>> On Mon, Sep 01, 2025 at 05:45:49AM +0200, Krzysztof Kozlowski wrote:
> >>>> On Fri, Aug 29, 2025 at 01:48:15AM +0300, Dmitry Baryshkov wrote:
> >>>>> The SM6350 doesn't have MST support, as such it is not compatible with
> >>>>> the SM8350 platform. Add new entry for SM6350 with fallback to SC7180
> >>>>> (which belongs to the same generation and also doesn't have MST
> >>>>> support).
> >>>>>
> >>>>> Fixes: 39086151593a ("dt-bindings: display: msm: dp-controller: document SM6350 compatible")
> >>>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> >>>>> ---
> >>>>> .../devicetree/bindings/display/msm/dp-controller.yaml | 14 +++++++++++++-
> >>>>> 1 file changed, 13 insertions(+), 1 deletion(-)
> >>>>>
> >>>>> diff --git a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> >>>>> index aed3bafa67e3c24d2a876acd29660378b367603a..0f814aa6f51406fdbdd7386027f88dfbacb24392 100644
> >>>>> --- a/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> >>>>> +++ b/Documentation/devicetree/bindings/display/msm/dp-controller.yaml
> >>>>> @@ -31,13 +31,25 @@ properties:
> >>>>> - qcom,sm8650-dp
> >>>>> - items:
> >>>>> - enum:
> >>>>> - - qcom,sar2130p-dp
> >>>>> - qcom,sm6350-dp
> >>>>> + - const: qcom,sc7180-dp
> >>>>> +
> >>>>> + # deprecated entry for compatibility with old DT
> >>>>> + - items:
> >>>>> + - enum:
> >>>>> + - qcom,sm6350-dp
> >>>>> + - const: qcom,sm8350-dp
> >>>>> + deprecated: true
> >>>>
> >>>> If it is only about bindings then there is little benefit in keeping
> >>>> this, just drop this case. However you cannot drop it from DTS, so this
> >>>> is a bit pointless.
> >>>
> >>> Our plan is:
> >>> - land updated DT bindings, describing MST clocks on MST-enabled
> >>> platforms,
> >>> - land updated DTS, adding MST clocks where applicable,
> >>
> >> This part breaks all out-of-tree users of DTS.
> >
> > User of which one? SM6350 or all DTS?
>
> SM6350.
>
> >
> > It extends the ABI, so no, it shouldn't. We add regions and clocks,
>
> No, it does not extend the ABI. You are changing the fallback, so you
> are changing the ABI.
I was thinking about the whole patchset: adding DP MST-specific clocks
and regions. For this particular patch you are correct.
>
>
> > existing users can use the previously defined feature set.
> >
> > Anyway, is it about adding more explicit note to the cover letter and/or
> > commit message or would you have any other proposal on how to handle the
> > issue?
>
> Please be explicit if Linux was working with the old fallback or not. In
> the DTS change be explicit about impact, e.g. that sc7180 fallback is
> there since forever.
Ack.
>
> >
> >>
> >>> - land driver changes, keeping legacy support for non-MST DTs on
> >>> MST-enabled SoCs
> >>>
> >>>>
> >>>> Lack of MST support is not informative enough to claim it is not
> >>>> compatible with 8350. For example if it was working fine via fallback,
> >>>> then that statement is simply not correct.
> >>>>
> >>>> And it HAD to work fine, because there is nothing binding to
> >>>> qcom,sm6350-dp.
> >>>
> >>> It is working fine since currently we don't have MST support on the
> >>> driver side (nor do we describe MST clocks in DT). It's true that the
> >>> driver will have to handle non-MST DT for SM8350. However I definitely
> >>> don't want to describe both cases in the bindings. SM6350 is not going
> >>> to be compatible with the MST-enabled SM8350 schema.
> >>
> >> The question is rather: is SM6350 going to be compatible (working) with
> >> MST-enabled drivers.
> >
> > If somebody implements e.g. U-Boot DP MST support after we land DP MST
> > bindings, I would not guarantee that. SM8350 will already have second
> > stream clock.
>
>
> Having second stream clock does not mean device stops working with Linux
> kernel. I can easily imagine both cases after adding MST to the drivers,
> the SM6350 stops working or keeps working...
It will keep on working, since we need to support old MST-less
sm8350.dtsi.
--
With best wishes
Dmitry
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