Re: [PATCH] arm64: dts: imx95: Use GPU_CGC as core clock for GPU

[Rain Yang <jiyu.yang@oss.nxp.com>]

On Tue, Dec 30, 2025 at 03:17:44PM +0100, Marek Vasut wrote:
>On 12/30/25 3:53 AM, Rain Yang wrote:
>> On Tue, Dec 30, 2025 at 02:53:38AM +0100, Marek Vasut wrote:
>> > On 12/8/25 3:02 AM, Rain Yang wrote:
>> > 
>> > > > > Okay, I’ll submit a patch later.
>> > > > > The commit message should reflect that only CLK_GPU_CGC is enabled.
>> > > > 
>> > > > The commit message , and this change , is unrelated to GPUAPB clock.
>> > > The commit message is ambiguous. Could you clarify which parent clock
>> > > you are referring to, and whether it can be enabled by CLK_GPU_CGC?
>> > > If it was CLK_GPU, CLK_GPU_CGC can't be able to control it.
>> > 
>> > The commit message clearly states "These new GPU_CGC clock
>> > gate the existing GPU clock." and "GPU_CGC as well as its parent GPU clock."
>> > , I don't perceive any ambiguity, sorry.
>> > 
>> > Frankly, the whole GPUAPB discussion is entirely unrelated and it only stalls
>> > application of this bugfix and keeps upstream broken. This is not helping.
>> > 
>> > So unless there is anything in particular that is on-topic and prevents this
>> > patch from being applied, it would be good to apply it, otherwise the GPU on
>> > MX95 in mainline Linux is not working.
>> Hi Marek,
>> 
>> I’m not opposed to this patch being merged into mainline, but the commit
>> message needs to be accurate. the parent CLK_GPU cannot be enabled or
>> disabled externally. The last sentence should clearly state:
>
>Look here, this is what you can do with the MX95 SM:
>
>"
>>$ clock.r
>...
>083: gpuapb               =  on,  133333333Hz
>084: gpu                  =  on,  800000000Hz
>...
>174: gpu_cgc              =  on,  800000000Hz
>
>>$ clock.w gpu_cgc off
>>$ clock.w gpu off
>>$ clock.w gpuapb off
>
>>$ clock.r
>...
>083: gpuapb               = off,  133333333Hz
>084: gpu                  = off,  800000000Hz
>...
>174: gpu_cgc              = off,  800000000Hz
>"
>
>Notice how all clock are disabled, including GPU clock.
>
>That does not agree with your statement.
>
>> When the panthor driver enables the GPU core clock, it enables the GPU_CGC.
>
>It also enables all disabled parent clock in the process, which includes the
>GPU clock.
>
>> This ensures the description reflects the actual hardware behavior and
>> avoids confusion for future maintainers.
>> Thanks for addressing this issue — once the commit message is corrected,
>> I’m fine with this going in.
>
>See above.

Hi Marek,
Based on the instructions you gave, I’d put it this way, even though the
CLK_GPU clock can only be controlled internally.

I’m fine with your patch now.