On 13.12.2022 16:23, Doug Anderson wrote:
> Hi,
>
> On Mon, Dec 12, 2022 at 4:24 PM Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> wrote:
>>
>> Add support for matching QFPROM fuse values to get the correct speed bin
>> on A650 (SM8250) GPUs.
>>
>> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
>> ---
>> drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 17 +++++++++++++++++
>> 1 file changed, 17 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> index 2c1630f0c04c..f139ec57c32d 100644
>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> @@ -1887,6 +1887,20 @@ static u32 a640_get_speed_bin(u32 fuse)
>> return UINT_MAX;
>> }
>>
>> +static u32 a650_get_speed_bin(u32 fuse)
>> +{
>> + if (fuse == 0)
>> + return 0;
>> + else if (fuse == 1)
>> + return 1;
>> + else if (fuse == 2)
>> + return 2;
>> + else if (fuse == 3)
>> + return 3;
>> +
>> + return UINT_MAX;
>
> Unlike some of the other functions, you don't need any complexity. Just do:
>
> if (fuse <= 3)
> return fuse;
>
> return UINT_MAX;
I'd prefer to keep it open-coded, it's just 8150 and 8250 that have
these simple fuse values, other SoCs have random numbers (check A618/
619 above, for example).. Plus the returned values might as well be
made-up, as it's just for opp matching.
>
>
> I'd also suggest that perhaps "UINT_MAX" isn't exactly the right
> return value for when we have an unrecognized fuse. The return type
> for the function is "u32" which is a fixed size type. UINT_MAX,
> however, is a type that is automatically sized by the compiler. Though
> it's unlikely, theoretically a compiler could be configured such that
> "unsigned int" was something other than 32 bits. Ideally either the
> return type would be changed to "unsigned int" or you'd return
> 0xffffffff as the sentinel value.
That's out of the scope of this patch, as it concerns all the
speedbin-supported GPUs. The returned value feeds 1<<ret, which
should be capped a bit lower than UINT_MAX, anyway. But I can
look into that in a separate patchset.
Konrad
>
> -Doug
