Il 18/02/25 13:44, Friday Yang (杨阳) ha scritto:
On Fri, 2025-01-24 at 17:31 +0000, Conor Dooley wrote:
On Wed, Jan 22, 2025 at 07:40:12AM +0000, Friday Yang (杨阳) wrote:
On Tue, 2025-01-21 at 17:30 +0000, Conor Dooley wrote:
On Tue, Jan 21, 2025 at 02:50:40PM +0800, Friday Yang wrote:
SMI LARBs require reset functions when applying clamp
operations.
Add '#reset-cells' for the clock controller located in image,
camera
and IPE subsystems.
A new required property is an abi break, please explain why this
is
required.
You never answered this part. From a quick check, looks like the
change
you made will cause probe failures if the resets are not present?
Maybe
I misread the driver code in my quick skim - but that is the
implication
of a new required property, so I didn't dig super far.
Adding new properties that break a driver is not really acceptable,
so I
hope I made a mistake there.
Sorry to reply late.
This is a known bus glitch issue. It worked because MediaTek has
provided patches 1, 2 and 3. In other word, it can not work
without patches 1, 2 and 3.
1.
https://lore.kernel.org/all/20240327055732.28198-1-yu-chang.lee@xxxxxxxxxxxx/
2.
https://lore.kernel.org/all/20240327055732.28198-2-yu-chang.lee@xxxxxxxxxxxx/
3.
https://lore.kernel.org/all/20240327055732.28198-3-yu-chang.lee@xxxxxxxxxxxx/
Patches 1, 2 and 3 have been previously reviewed, and the reviewers
provided the following comments:
4.
https://lore.kernel.org/all/CAFGrd9qZhObQXvm2_abqaX83xMLqxjQETB2=wXpobDWU1CnvkA@xxxxxxxxxxxxxx/
5.
https://lore.kernel.org/all/CAPDyKFpokXV2gJDgowbixTvOH_5VL3B5H8eyhP+KJ5Fasm2rFg@xxxxxxxxxxxxxx/
As I mentioned earlier, SMI clamp and reset operations should be
implemented in SMI driver rather than the PM driver. Additionally, the
reset operations have already been implemented in the clock control
driver. There is no need to submit duplicate code.
To address this, I have provided patches 6, 7 to replace patches 1, 2,
and 3, as I believe this approach aligns more closely with the
reviewers' requirements.
6.
https://lore.kernel.org/lkml/20250121065045.13514-1-friday.yang@xxxxxxxxxxxx/
7.
https://lore.kernel.org/lkml/20250121064934.13482-1-friday.yang@xxxxxxxxxxxx/
What's more, I have tested the patch 6, 7 in MediaTek MT8188 SoC.
It could work well. If you have any questions, please feel free to
contact me.
What are "SMI LARBs"? Why did things previously work
without
acting as a reset controller?
The background can refer to the discussion in the following link:
https://lore.kernel.org/all/CAFGrd9qZhObQXvm2_abqaX83xMLqxjQETB2=wXpobDWU1CnvkA@xxxxxxxxxxxxxx/
https://lore.kernel.org/all/CAPDyKFpokXV2gJDgowbixTvOH_5VL3B5H8eyhP+KJ5Fasm2rFg@xxxxxxxxxxxxxx/
SMI clamp and reset operations should be implemented in SMI driver
instead of PM driver.
So the answer to how it worked previously was that nothing actually
used
this multimedia interface?
Your commit message needs to explain why a new required property is
okay
and why it was not there before.
This conversation slipped through the cracks - wanted to reply to this quite a bit
of time ago but then for whatever reason .... eh here we are :-)
Anyway.
The cleanest option to get the glitching situation to get resolved is probably
exactly the one that Friday proposed with this series...
I agree that the commit needs a proper description, though, and even though the
drivers were never actually used (so it's not a huge problem - as in - no device
gets broken when this is merged), it's still an ABI breakage, and that has to be
justified with a good reason.
The good reason is that there's a hardware bug that you're trying to resolve here
and that emerged only after the initial upstreaming of this binding (do *not*
mention drivers in DT bindings, those describe the hardware, not software!), and
the only way to resolve this situation is by resetting the Local Arbiter (LARB)
of the cam/img/ipe macro-blocks.
Failing to do this, the hardware is going to be unstable during high/dynamic load
conditions.
So, just describe the problem and how you're solving it in the commit description:
that's going to be okay and justifying everything that you're doing here.
I'm sorry for chiming in that late, btw.
Cheers,
Angelo
Thanks,
Conor.
I previously added the SMI reset control driver. However, the
reviewer's comments are correct, these functions have already
been implemented in the clock control driver. There is no need
to submit duplicate code.
https://lore.kernel.org/lkml/20241120063305.8135-2-friday.yang@xxxxxxxxxxxx/
https://lore.kernel.org/lkml/20241120063305.8135-3-friday.yang@xxxxxxxxxxxx/
On the MediaTek platform, the SMI block diagram like this:
DRAM
|
EMI(External Memory Interface)
| |
MediaTek IOMMU(Input Output Memory Management Unit)
| |
SMI-Common(Smart Multimedia Interface Common)
|
+----------------+------------------+
| | |
| | |
| | |
| | |
| | |
larb0 SMI-Sub-Common0 SMI-Sub-Common1
| | | | |
larb1 larb2 larb3 larb7 larb9
The SMI-Common connects with SMI LARBs and IOMMU. The maximum LARBs
number that connects with a SMI-Common is 8. If the engines number
is
over 8, sometimes we use a SMI-Sub-Common which is nearly same with
SMI-Common. It supports up to 8 input and 1 output(SMI-Common has 2
output).
Signed-off-by: Friday Yang <friday.yang@xxxxxxxxxxxx>
---
.../bindings/clock/mediatek,mt8188-clock.yaml | 21
+++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git
a/Documentation/devicetree/bindings/clock/mediatek,mt8188-
clock.yaml
b/Documentation/devicetree/bindings/clock/mediatek,mt8188-
clock.yaml
index 860570320545..2985c8c717d7 100644
--- a/Documentation/devicetree/bindings/clock/mediatek,mt8188-
clock.yaml
+++ b/Documentation/devicetree/bindings/clock/mediatek,mt8188-
clock.yaml
@@ -57,6 +57,27 @@ required:
- reg
- '#clock-cells'
+allOf:
+ - if:
+ properties:
+ compatible:
+ contains:
+ enum:
+ - mediatek,mt8188-camsys-rawa
+ - mediatek,mt8188-camsys-rawb
+ - mediatek,mt8188-camsys-yuva
+ - mediatek,mt8188-camsys-yuvb
+ - mediatek,mt8188-imgsys-wpe1
+ - mediatek,mt8188-imgsys-wpe2
+ - mediatek,mt8188-imgsys-wpe3
+ - mediatek,mt8188-imgsys1-dip-nr
+ - mediatek,mt8188-imgsys1-dip-top
+ - mediatek,mt8188-ipesys
+
+ then:
+ required:
+ - '#reset-cells'
+
additionalProperties: false
examples:
--
2.46.0
