Re: [PATCH v2] dt-bindings: arm: mediatek: mmsys: change compatible for MT8195

From: Matthias Brugger
Date: Wed Sep 14 2022 - 10:32:18 EST




On 26/08/2022 17:39, Matthias Brugger wrote:


On 26/08/2022 09:13, Bo-Chen Chen wrote:
On Fri, 2022-08-26 at 15:00 +0800, Krzysztof Kozlowski wrote:
On 26/08/2022 05:07, Bo-Chen Chen wrote:
On Thu, 2022-08-25 at 22:57 +0800, Matthias Brugger wrote:

On 25/08/2022 11:14, Bo-Chen Chen wrote:
From: "Jason-JH.Lin" <jason-jh.lin@xxxxxxxxxxxx>

For previous MediaTek SoCs, such as MT8173, there are 2 display
HW
pipelines binding to 1 mmsys with the same power domain, the
same
clock driver and the same mediatek-drm driver.

For MT8195, VDOSYS0 and VDOSYS1 are 2 display HW pipelines
binding
to
2 different power domains, different clock drivers and
different
mediatek-drm drivers.

Moreover, Hardware pipeline of VDOSYS0 has these components:
COLOR,
CCORR, AAL, GAMMA, DITHER. They are related to the PQ (Picture
Quality)
and they makes VDOSYS0 supports PQ function while they are not
including in VDOSYS1.

Hardware pipeline of VDOSYS1 has the component ETHDR (HDR
related
component). It makes VDOSYS1 supports the HDR function while
it's
not
including in VDOSYS0.

To summarize0:
Only VDOSYS0 can support PQ adjustment.
Only VDOSYS1 can support HDR adjustment.

Therefore, we need to separate these two different mmsys
hardwares
to
2 different compatibles for MT8195.

Fixes: 81c5a41d10b9 ("dt-bindings: arm: mediatek: mmsys: add
mt8195
SoC binding")
Signed-off-by: Jason-JH.Lin <jason-jh.lin@xxxxxxxxxxxx>
Signed-off-by: Bo-Chen Chen <rex-bc.chen@xxxxxxxxxxxx>
---
Changes for v2:
1. Add hardware difference for VDOSYS0 and VDOSYS1 in commit
message.
---
.../devicetree/bindings/arm/mediatek/mediatek,mmsys.yaml
|
3 ++-
   1 file changed, 2 insertions(+), 1 deletion(-)

diff --git
a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys
.yam
l
b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys
.yam
l
index 6ad023eec193..bfbdd30d2092 100644
---
a/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys
.yam
l
+++
b/Documentation/devicetree/bindings/arm/mediatek/mediatek,mmsys
.yam
l
@@ -31,7 +31,8 @@ properties:
                 - mediatek,mt8183-mmsys
                 - mediatek,mt8186-mmsys
                 - mediatek,mt8192-mmsys
-              - mediatek,mt8195-mmsys
+              - mediatek,mt8195-vdosys0

Thanks for you patch. As I mentioned on v1, I propose to set
mediatek,mt8195-mmsys as fallback for mediatek,mt8195-vdosys0 to
not
break
backwards compatibility.

Apart from that, the binding change will need some changes to
support
the new
binding. Please provide these together with this patch.

Regards,
Matthias


Hello Matthias,

Thanks for your comments.
The purpose of this patch is to confirm we can separate mt8195
mmsys
into two compatibles. I think this modification is accepted.

No, it is not accepted following Matthias comments. You received my
ack
based on assumption that ABI break is perfectly ok for platform
maintainer, as he has decisive voice. If anyone is not happy with a
ABI
break, then his concerns must be addressed.

So let it be specific:
NAK.


After this, I think Jason-JH will push another series with this
binding
patch.

I don't know what do you mean here - another series on top of wrong
patch?


Hello Krzysztof,

For this mt8195 mmsys binding separation, we still need to modify
driver for this. The reason I send this patch is to confirm we can do
this binding modification and I also think we can not pick this patch
here.

We will push another series and it contains modification of binding and
drivers. (The series will push by Jason-JH Lin)


Sounds good. So lets wait for Jason-JH Lin to send this series and we can go on with the review.


Just to be sure, this has not happened yet, correct?

Regards,
Matthias

Thanks!
Matthias

Maybe I should use "RFC" for this series, and I think it's more
correct.

BRs,
Bo-Chen

In Jason-JH's series, we will modify mmsys driver based on this.
And I think we don't need to keep "mediatek,mt8195-mmsys" if we
also
modify mmsys drivers in the same series.

This does not fux ABI break and broken bisectability.


Is it ok that postpones to pick this patch until we finish review
follow-up series?


No. You got a clear review to fix.

Best regards,
Krzysztof