Re: [PATCH v2 04/11] drm/msm: adreno: add GMU_BW_VOTE feature flag

[Akhil P Oommen <quic_akhilpo@quicinc.com>]

On 11/25/2024 1:46 PM, Neil Armstrong wrote:
> On 23/11/2024 20:43, Akhil P Oommen wrote:
>> On Tue, Nov 19, 2024 at 06:56:39PM +0100, Neil Armstrong wrote:
>>> The Adreno GMU Management Unit (GNU) can also scale the DDR Bandwidth
>>> along the Frequency and Power Domain level, but by default we leave the
>>> OPP core vote for the interconnect ddr path.
>>>
>>> While scaling via the interconnect path was sufficient, newer GPUs
>>> like the A750 requires specific vote paremeters and bandwidth to
>>> achieve full functionality.
>>>
>>> While the feature will require some data in a6xx_info, it's safer
>>> to only enable tested platforms with this flag first.
>>>
>>> Add a new feature enabling DDR Bandwidth vote via GMU.
>>>
>>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
>>> ---
>>>   drivers/gpu/drm/msm/adreno/adreno_gpu.h | 1 +
>>>   1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.h b/drivers/gpu/
>>> drm/msm/adreno/adreno_gpu.h
>>> index
>>> 4702d4cfca3b58fb3cbb25cb6805f1c19be2ebcb..394b96eb6c83354ae008b15b562bedb96cd391dd 100644
>>> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.h
>>> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
>>> @@ -58,6 +58,7 @@ enum adreno_family {
>>>   #define ADRENO_FEAT_HAS_HW_APRIV        BIT(0)
>>>   #define ADRENO_FEAT_HAS_CACHED_COHERENT        BIT(1)
>>>   #define ADRENO_FEAT_PREEMPTION            BIT(2)
>>> +#define ADRENO_FEAT_GMU_BW_VOTE            BIT(3)
>>
>> Do we really need a feature flag for this? We have to carry this for
>> every
>> GPU going forward. IB voting is supported on all GMUs from A6xx GEN2 and
>> newer. So we can just check that along with whether the bw table is
>> dynamically generated or not.
> 
> It depends on the bw table _and_ the a6xx_info.gmu table, I don't want to
> check both in all parts on the driver.
> 
Thats fine then.

-Akhil.

> Neil
> 
>>
>> -Akhil
>>
>>>     /* Helper for formating the chip_id in the way that userspace
>>> tools like
>>>    * crashdec expect.
>>>
>>> -- 
>>> 2.34.1
>>>
> 
>