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

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Message-ID: <b4f283ce-5be1-4d2f-82e2-e9c3be22a37f@oss.qualcomm.com>
Date: Thu, 14 Aug 2025 13:22:57 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Neil Armstrong <neil.armstrong@...aro.org>,
        Rob Clark <robin.clark@....qualcomm.com>, Sean Paul <sean@...rly.run>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jessica.zhang@....qualcomm.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Subject: Re: [PATCH v2] drm/msm: adreno: a6xx: enable GMU bandwidth voting for
 x1e80100 GPU

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@....qualcomm.com>
>>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.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@....qualcomm.com>
> 
> Actually no, BIT(3) is for the CPU (OS), GPU should use BIT(2)

This is *very* platform-dependent, goes without saying..

I see BIT(2) is also valid for X1P4

Konrad