linux-kernel - Re: [PATCH 04/17] drm/msm/a6xx: Poll additional DRV status

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Message-ID: <002eb889-87cb-4b8c-98fb-6826c6977868@oss.qualcomm.com>
Date: Thu, 24 Jul 2025 00:58:08 +0530
From: Akhil P Oommen <akhilpo@....qualcomm.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        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
Subject: Re: [PATCH 04/17] drm/msm/a6xx: Poll additional DRV status

On 7/23/2025 3:31 PM, Konrad Dybcio wrote:
> On 7/20/25 2:16 PM, Akhil P Oommen wrote:
>> A7XX_GEN2 generation has additional TCS slots. Poll the respective
>> DRV status registers before pm suspend.
>>
>> Signed-off-by: Akhil P Oommen <akhilpo@....qualcomm.com>
>> ---
>>  drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 16 ++++++++++++++++
>>  1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>> index 790ef2f94a0b0cd40433d7edb6a89e4f04408bf5..3bebb6dd7059782ceca29f2efd2acee24d3fc930 100644
>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>> @@ -987,6 +987,22 @@ static void a6xx_gmu_rpmh_off(struct a6xx_gmu *gmu)
>>  		val, (val & 1), 100, 10000);
>>  	gmu_poll_timeout_rscc(gmu, REG_A6XX_RSCC_TCS3_DRV0_STATUS + seqmem_off,
>>  		val, (val & 1), 100, 1000);

1000us here is a typo and I copied the same mistake below. I will update
all of these timeout values to a common 10000us in the next revision.

>> +
>> +	if (!adreno_is_a740_family(adreno_gpu))
>> +		return;
>> +
>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS4_DRV0_STATUS + seqmem_off,
>> +		val, (val & 1), 100, 10000);
>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS5_DRV0_STATUS + seqmem_off,
>> +		val, (val & 1), 100, 10000);
>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS6_DRV0_STATUS + seqmem_off,
>> +		val, (val & 1), 100, 10000);
>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS7_DRV0_STATUS + seqmem_off,
>> +		val, (val & 1), 100, 1000);
>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS8_DRV0_STATUS + seqmem_off,
>> +		val, (val & 1), 100, 10000);
>> +	gmu_poll_timeout_rscc(gmu, REG_A7XX_RSCC_TCS9_DRV0_STATUS + seqmem_off,
>> +		val, (val & 1), 100, 1000);
> 
> FWIW there are places downstream where it polls for 1 ms
> (gen7_gmu_pwrctrl_suspend) / 2 ms (gen7_gmu_power_off) ms (as opposed
> to 1 or 10 ms here), but the timeouts are all the same across registers
> (unlike TCS3 and TCS9 above)
> 
> Ultimately it's a timeout, so a value too big shouldn't matter, but
> let's make sure the other threshold is ok

They are fine. We can try to reduce the timeout 2ms in a separate patch
outside of this series.

-Akhil.

> 
> Konrad