Re: [PATCH v4 0/7] Add SDM670 camera subsystem

[Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>]

Hi Bryan, Richard,

On 9/6/24 15:19, Bryan O'Donoghue wrote:
> On 06/09/2024 03:36, Richard Acayan wrote:
>> On Thu, Sep 05, 2024 at 10:09:34PM +0200, Andi Shyti wrote:
>>> Hi Richard,
>>>
>>> On Tue, Sep 03, 2024 at 10:04:49PM GMT, Richard Acayan wrote:
>>>> This adds support for the camera subsystem on the Snapdragon 670.
>>>>
>>>> As of next-20240902, camss seems to be a bit broken, but the same series
>>>> works on stable (although it is much less reliable now that the CCI clock
>>>> frequency is not being assigned).
>>>
>>> I am not understanding this bit: is this series making it better
>>> or not? Can you please clarify what is broken, what is less
>>> reliable and what works?
>>
>> When applying this camss series and some camera sensor patches on
>> linux-next, the Pixel 3a seems to hang when camera capture starts.
>>
>> When applying the same patches on stable, the camera does not cause the
>> Pixel 3a to hang.
> 
> Right so -next isn't stable that's not exactly a revelation.
> 
> 
>> When these device tree properties from the previous series were removed:
>>
>> 			assigned-clocks = <&camcc CAM_CC_CCI_CLK>;
>> 			assigned-clock-rates = <37500000>;
>>
>> the CCI would sometimes fail to probe with the error:
> 
> Right, we don't have clk_set_rate in the cci driver.
> 
> Maybe just leave the assigned clock for this submission and we can do a
> sweep of fixes to CCI at a later stage including setting the clock
> instead of having it be assigned.

first of all it would be nice to confirm that the setting of a particular
clock frequency is actually needed.

Fortunately it's pretty trivial to check it in runtime with a temporary
modification in the board dts file, namely disable CAMSS in board dts file,
but keep CCI enabled, then simply scan the bus with a regular "i2cdetect"
tool in runtime.

If i2cdetect on the CCI bus works only for 37.5MHz clock frequency, then it
is needed, otherwise (and this is my expectation) it is not needed neither
in the dtsi files nor in the driver.

>>
>> 	[   51.572732] i2c-qcom-cci ac4a000.cci: deferred probe timeout, ignoring dependency
>> 	[   51.572769] i2c-qcom-cci ac4a000.cci: probe with driver i2c-qcom-cci failed with error -110
>>
>> On further testing, the rate can be set to 19.2 MHz, and there would be
>> no failure (or rather, it wouldn't happen often enough for me to witness
>> it).
> 
> That's expected 19.2 and 37.5 MHz are supported by CAMCC for your part.
>

I read it as the setting of 37.5MHz clock frequency is not needed, please
correct me.

--
Best wishes,
Vladimir