[PATCH] drm/mgag200: Fix gamma lut not initialized.

[Jocelyn Falempe]

On 10/05/2023 11:15, Thomas Zimmermann wrote:
> Hi,
> 
> oh great! Thank you for fixing this bug. And sorry that I broke it.
> 
> Am 10.05.23 um 10:54 schrieb Jocelyn Falempe:
>> When mgag200 switched from simple KMS to regular atomic helpers,
>> the initialization of the gamma settings was lost.
>> This leads to a black screen, if the bios/uefi doesn't use the same
>> pixel color depth.
>>
>> Link: https://bugzilla.redhat.com/show_bug.cgi?id=2171155
>> Fixes: 1baf9127c482 ("drm/mgag200: Replace simple-KMS with regular 
>> atomic helpers")
>> Tested-by: Phil Oester <kernel at linuxace.com>
>> Signed-off-by: Jocelyn Falempe <jfalempe at redhat.com>
> 
> Also needs:
> 
> Cc: <stable at vger.kernel.org> # v6.1+

Should I send a v2 with this added ?
> 
> In terms of what it does:
> 
> Reviewed-by: Thomas Zimmermann <tzimmermann at suse.de>
> 
> but the patch is apparently for against an old version. (v6.1?) The code 
> in mgag200_crtc_helper_atomic_enable has changed quite a bit.

Yes, I based it on the culprit commit 1baf9127c482, but it applies 
cleanly with git am -3 on top of v6.3

> 
> Best regards
> Thomas
> 
>> ---
>>   drivers/gpu/drm/mgag200/mgag200_mode.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c 
>> b/drivers/gpu/drm/mgag200/mgag200_mode.c
>> index 461da1409fdf..911d46741e40 100644
>> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
>> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
>> @@ -819,6 +819,11 @@ static void 
>> mgag200_crtc_helper_atomic_enable(struct drm_crtc *crtc,
>>       else if (mdev->type == G200_EV)
>>           mgag200_g200ev_set_hiprilvl(mdev);
>> +    if (crtc_state->gamma_lut)
>> +        mgag200_crtc_set_gamma(mdev, format, 
>> crtc_state->gamma_lut->data);
>> +    else
>> +        mgag200_crtc_set_gamma_linear(mdev, format);
>> +
>>       mgag200_enable_display(mdev);
>>       if (mdev->type == G200_WB || mdev->type == G200_EW3)
>>
>> base-commit: 1baf9127c482a3a58aef81d92ae751798e2db202
> 

-- 

Jocelyn