linux-kernel - Re: [PATCH] drm/msm/a6xx: Correct the highestbank configuration

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Message-ID: <9a9ec81d-f963-8d71-d6aa-d32956788d94@codeaurora.org>
Date:   Fri, 31 Jan 2020 13:29:54 +0530
From:   Akhil P Oommen <akhilpo@...eaurora.org>
To:     freedreno@...ts.freedesktop.org, dri-devel@...edesktop.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        smasetty@...eaurora.org
Subject: Re: [PATCH] drm/msm/a6xx: Correct the highestbank configuration

On 1/24/2020 11:56 PM, Jordan Crouse wrote:
> On Fri, Jan 24, 2020 at 05:50:11PM +0530, Akhil P Oommen wrote:
>> Highest bank bit configuration is different for a618 gpu. Update
>> it with the correct configuration which is the reset value incidentally.
>>
>> Signed-off-by: Akhil P Oommen <akhilpo@...eaurora.org>
>> Signed-off-by: Sharat Masetty <smasetty@...eaurora.org>
>> ---
>>   drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 10 ++++++----
>>   1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> index daf0780..536d196 100644
>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> @@ -470,10 +470,12 @@ static int a6xx_hw_init(struct msm_gpu *gpu)
>>   	/* Select CP0 to always count cycles */
>>   	gpu_write(gpu, REG_A6XX_CP_PERFCTR_CP_SEL_0, PERF_CP_ALWAYS_COUNT);
>>   
>> -	gpu_write(gpu, REG_A6XX_RB_NC_MODE_CNTL, 2 << 1);
>> -	gpu_write(gpu, REG_A6XX_TPL1_NC_MODE_CNTL, 2 << 1);
>> -	gpu_write(gpu, REG_A6XX_SP_NC_MODE_CNTL, 2 << 1);
>> -	gpu_write(gpu, REG_A6XX_UCHE_MODE_CNTL, 2 << 21);
>> +	if (adreno_is_a630(adreno_gpu)) {
>> +		gpu_write(gpu, REG_A6XX_RB_NC_MODE_CNTL, 2 << 1);
>> +		gpu_write(gpu, REG_A6XX_TPL1_NC_MODE_CNTL, 2 << 1);
>> +		gpu_write(gpu, REG_A6XX_SP_NC_MODE_CNTL, 2 << 1);
>> +		gpu_write(gpu, REG_A6XX_UCHE_MODE_CNTL, 2 << 21);
>> +	}
> it shouldn't come as a surprise that everything in the a6xx family is going to
> have a highest bank bit setting. Even though the a618 uses the reset value, I
> think it would be less confusing to future folks if we explicitly program it:
>
> if (adreno_is_a630(adreno_dev))
>    hbb = 2;
> else
>    hbb = 0;

I think it would be better if we keep this in the adreno_info. Yes, this 
would waste a tiny bit of space for other gpu
entries in the gpulist. It is also possible to move this to a separate 
struct and keep a pointer to it in the adreno_info.
But that is something we should try when there are more a6xx specific 
configurations in future.

I have a new patch, but testing it is taking longer that I expected. I 
will share it as soon as possible.

> ....
>
> Jordan
>
Akhil

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