On 16/08/2023 10:45, Steven Price wrote:
> On 16/08/2023 02:42, David Michael wrote:
>> Encountered on an ARM Mali-T760 MP4, attempting to read the nvmem
>> variable can also return EOPNOTSUPP instead of ENOENT when speed
>> binning is unsupported.
>>
>> Cc: <stable@xxxxxxxxxxxxxxx>
>> Fixes: 7d690f936e9b ("drm/panfrost: Add basic support for speed binning")
>> Signed-off-by: David Michael <fedora.dm0@xxxxxxxxx>
>
> Reviewed-by: Steven Price <steven.price@xxxxxxx>
And pushed to drm-misc-fixes.
Thanks,
Steve
>> ---
>>
>> Hi,
>>
>> I upgraded an old Chromebook (veyron-minnie) to 6.4, and it fell back to
>> software rendering with "Cannot read speed-bin (-95)." in dmesg. Does
>> this error code also make sense to skip? Hardware acceleration seems to
>> work as it did previously with this change.
>
> I believe this is because the kernel is compiled without CONFIG_NVMEM so
> the stub function is returning EOPNOTSUPP.
>
> Since most platforms don't support speed binning just continuing is the
> correct approach on those. For platforms with speed binning this means
> the binning won't be applied if !CONFIG_NVMEM - but I don't think
> there's much we can do about that.
>
> Steve
>
>>
>> Thanks.
>>
>> David
>>
>> drivers/gpu/drm/panfrost/panfrost_devfreq.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
>> index 58dfb15a8757..e78de99e9933 100644
>> --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c
>> +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c
>> @@ -96,7 +96,7 @@ static int panfrost_read_speedbin(struct device *dev)
>> * keep going without it; any other error means that we are
>> * supposed to read the bin value, but we failed doing so.
>> */
>> - if (ret != -ENOENT) {
>> + if (ret != -ENOENT && ret != -EOPNOTSUPP) {
>> DRM_DEV_ERROR(dev, "Cannot read speed-bin (%d).", ret);
>> return ret;
>> }
>
