[PATCH 2/4] drm/amdgpu/display: don't assert in set backlight function

[Kazlauskas, Nicholas]

On 2021-03-04 1:41 p.m., Alex Deucher wrote:
> On Thu, Mar 4, 2021 at 1:33 PM Kazlauskas, Nicholas
> <nicholas.kazlauskas at amd.com> wrote:
>>
>> On 2021-03-04 12:41 p.m., Alex Deucher wrote:
>>> It just spams the logs.
>>>
>>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>>
>> This series in general looks reasonable to me:
>> Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
>>
>>> ---
>>>    drivers/gpu/drm/amd/display/dc/core/dc_link.c | 1 -
>>>    1 file changed, 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
>>> index fa9a62dc174b..974b70f21837 100644
>>> --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
>>> +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
>>> @@ -2614,7 +2614,6 @@ bool dc_link_set_backlight_level(const struct dc_link *link,
>>>                        if (pipe_ctx->plane_state == NULL)
>>>                                frame_ramp = 0;
>>>                } else {
>>> -                     ASSERT(false);
>>
>> Just a comment on what's actually going on here with this warning:
>>
>> Technically we can't apply the backlight level without a plane_state in
>> the context but the panel is also off anyway.
>>
>> I think there might be a bug here when the panel turns on and we're not
>> applying values set when it was off but I don't think anyone's reported
>> this as an issue.
>>
>> I'm not entirely sure if the value gets cached and reapplied with the
>> correct value later, but it's something to keep in mind.
> 
> It doesn't.  I have additional patches here to cache it:
> https://nam11.safelinks.protection.outlook.com/?url=https:%2F%2Fcgit.freedesktop.org%2F~agd5f%2Flinux%2Flog%2F%3Fh%3Dbacklight_wip&data=04%7C01%7Cnicholas.kazlauskas%40amd.com%7Cf259e9290b0e4ffbc87308d8df3d3121%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637504801203988045%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=4ROSclecKkfu2km3YeeM7sZK%2FP%2BcC8BajHSxJXQQCRw%3D&reserved=0
> 
> Alex

That's aligned with my expectations then.

I can take a peek at the branch and help review the patches.

Regards,
Nicholas Kazlauskas

> 
>>
>> Regards,
>> Nicholas Kazlauskas
>>
>>>                        return false;
>>>                }
>>>
>>>
>>
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