Re: [PATCH v2] drm/msm: adreno: a6xx: enable GMU bandwidth voting for x1e80100 GPU

[Akhil P Oommen <akhilpo@oss.qualcomm.com>]

On 9/8/2025 10:03 PM, Neil Armstrong wrote:
> On 08/09/2025 18:29, Akhil P Oommen wrote:
>> On 9/8/2025 9:52 PM, Konrad Dybcio wrote:
>>> On 8/18/25 9:17 AM, Akhil P Oommen wrote:
>>>> On 8/16/2025 3:45 AM, Dmitry Baryshkov wrote:
>>>>> On Thu, Aug 14, 2025 at 07:52:13PM +0200, Konrad Dybcio wrote:
>>>>>> On 8/14/25 6:38 PM, Akhil P Oommen wrote:
>>>>>>> On 8/14/2025 7:56 PM, Neil Armstrong wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> On 14/08/2025 13:22, Konrad Dybcio wrote:
>>>>>>>>> On 8/14/25 1:21 PM, Konrad Dybcio wrote:
>>>>>>>>>> On 7/31/25 12:19 PM, Konrad Dybcio wrote:
>>>>>>>>>>> On 7/25/25 10:35 AM, Neil Armstrong wrote:
>>>>>>>>>>>> The Adreno GPU Management Unit (GMU) can also scale DDR
>>>>>>>>>>>> Bandwidth
>>>>>>>>>>>> along
>>>>>>>>>>>> the Frequency and Power Domain level, but by default we
>>>>>>>>>>>> leave the
>>>>>>>>>>>> OPP core scale the interconnect ddr path.
>>>>>>>>>>>>
>>>>>>>>>>>> Declare the Bus Control Modules (BCMs) and the corresponding
>>>>>>>>>>>> parameters
>>>>>>>>>>>> in the GPU info struct to allow the GMU to vote for the
>>>>>>>>>>>> bandwidth.
>>>>>>>>>>>>
>>>>>>>>>>>> Reviewed-by: Dmitry Baryshkov
>>>>>>>>>>>> <dmitry.baryshkov@oss.qualcomm.com>
>>>>>>>>>>>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
>>>>>>>>>>>> ---
>>>>>>>>>>>> Changes in v2:
>>>>>>>>>>>> - Used proper ACV perfmode bit/freq
>>>>>>>>>>>> - Link to v1: https://lore.kernel.org/r/20250721-topic-
>>>>>>>>>>>> x1e80100-
>>>>>>>>>>>> gpu-bwvote-v1-1-946619b0f73a@linaro.org
>>>>>>>>>>>> ---
>>>>>>>>>>>>    drivers/gpu/drm/msm/adreno/a6xx_catalog.c | 11 +++++++++++
>>>>>>>>>>>>    1 file changed, 11 insertions(+)
>>>>>>>>>>>>
>>>>>>>>>>>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_catalog.c b/
>>>>>>>>>>>> drivers/
>>>>>>>>>>>> gpu/drm/msm/adreno/a6xx_catalog.c
>>>>>>>>>>>> index
>>>>>>>>>>>> 00e1afd46b81546eec03e22cda9e9a604f6f3b60..892f98b1f2ae582268adebd758437ff60456cdd5 100644
>>>>>>>>>>>> --- a/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
>>>>>>>>>>>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
>>>>>>>>>>>> @@ -1440,6 +1440,17 @@ static const struct adreno_info
>>>>>>>>>>>> a7xx_gpus[] = {
>>>>>>>>>>>>                .pwrup_reglist = &a7xx_pwrup_reglist,
>>>>>>>>>>>>                .gmu_chipid = 0x7050001,
>>>>>>>>>>>>                .gmu_cgc_mode = 0x00020202,
>>>>>>>>>>>> +            .bcms = (const struct a6xx_bcm[]) {
>>>>>>>>>>>> +                { .name = "SH0", .buswidth = 16 },
>>>>>>>>>>>> +                { .name = "MC0", .buswidth = 4 },
>>>>>>>>>>>> +                {
>>>>>>>>>>>> +                    .name = "ACV",
>>>>>>>>>>>> +                    .fixed = true,
>>>>>>>>>>>> +                    .perfmode = BIT(3),
>>>>>>>>>>>> +                    .perfmode_bw = 16500000,
>>>>>>>>>>>
>>>>>>>>>>> Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
>>>>>>>>>>
>>>>>>>>>> Actually no, BIT(3) is for the CPU (OS), GPU should use BIT(2)
>>>>>>>
>>>>>>> You are right that BIT(2) is GPU specific, but that support was
>>>>>>> commercialized from A7XX_GEN3. Anyway, the Win KMD uses BIT(2),
>>>>>>> so lets
>>>>>>> use that in Linux too.
>>>>>>>
>>>>>>> I know some docs show BIT(2) support, but lets not bring in untested
>>>>>>> configurations.
>>>>>>
>>>>>> Eh, then let's get the docs fixed if you don't trust them because
>>>>>> we can't
>>>>>> work like that..
>>>>>>
>>>>>> FWIW this is information from per-platform RPMh cmd-db data
>>>>>
>>>>> If it comes from cmd-db, then we should be requesting it from the
>>>>> cmd-db
>>>>> driver rather than hardcoding it here.
>>>
>>> No, what I meant is that there is a piece of configuration that reflects
>>> what goes into cmd-db as its compiled and that's where I found that
>>> information
>>>
>>>>
>>>> Not really. This should be under the control of GPU driver.
>>>> BIT(3) is correct for X1E.
>>>
>>> BIT(3) is for APPS, see the interconnect driver which also uses it.
>>> This will create conflicts and may cause unvotes when some other
>>> driver requests perf_mode through the ICC API, but the GPU is sitting
>>> idle.
> 
> Yeah gpu will vote via it's own bcm drv interface and they will be
> agregated in the rpmh.
> 
> It's basically the whole point of this gpu bandwidth voting via gmu.
> 
>>
>> No. GPU vote goes via a different DRV. So it is independent. Anyway, I
>> checked this further earlier. X1E platform doesn't implement any
>> perfmode vote. So both BIT(3) and BIT(2) are no-op and are ignored by
>> AOSS. ICC driver's vote too should be no-op on X1E.
> 
> So I can drop the ACV bcm or it's a compat for other SoCs ?

Lets leave it as it is just to keep it consistent. There is no harm.

-Akhil
 >
> Neil
> 
>>
>> -Akhil.
>>
>>>
>>> Konrad
>>
> 
L