RE: Backlight control broken on UM325 (OLED) on 5.15 (bisected)

["Li, Roman" <Roman.Li@amd.com>]

[Public]

Hi Samuel,

Can you please try: https://patchwork.freedesktop.org/patch/463485/ ?

Thanks,
Roman

> -----Original Message-----
> From: Samuel Čavoj <samuel@cavoj.net>
> Sent: Tuesday, November 16, 2021 8:33 AM
> To: Alex Deucher <alexdeucher@gmail.com>
> Cc: Deucher, Alexander <Alexander.Deucher@amd.com>; Li, Sun peng (Leo)
> <Sunpeng.Li@amd.com>; Li, Roman <Roman.Li@amd.com>; Maling list - DRI
> developers <dri-devel@lists.freedesktop.org>; LKML <linux-
> kernel@vger.kernel.org>; amd-gfx list <amd-gfx@lists.freedesktop.org>
> Subject: Re: Backlight control broken on UM325 (OLED) on 5.15 (bisected)
>
> Hi Alex,
>
> thank you for your response.
>
> On 15.11.2021 10:43, Alex Deucher wrote:
> > [...]
> >
> > That patch adds support for systems with multiple backlights.  Do you
> > have multiple backlight devices now?  If so, does the other one work?
>
> No, there is still only one backlight device -- amdgpu_bl0.
> >
> > Can you also try this patch?
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > index 4811b0faafd9..67163c9d49e6 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > @@ -854,8 +854,8 @@ int amdgpu_acpi_init(struct amdgpu_device *adev)
> >                 if (amdgpu_device_has_dc_support(adev)) {  #if
> > defined(CONFIG_DRM_AMD_DC)
> >                         struct amdgpu_display_manager *dm = &adev->dm;
> > -                       if (dm->backlight_dev[0])
> > -                               atif->bd = dm->backlight_dev[0];
> > +                       if (dm->backlight_dev[1])
> > +                               atif->bd = dm->backlight_dev[1];
> >  #endif
> >                 } else {
> >                         struct drm_encoder *tmp;
> >
>
> There is no difference in behaviour after applying the patch.
>
> Samuel
>
> >
> > Alex
> >
> > >
> > > Regards,
> > > Samuel Čavoj
> > >
> > > [0]:
> > > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fww
> > >
> w.reddit.com%2Fr%2FAMDLaptops%2Fcomments%2Fqst0fm%2Fafter_updating
> _t
> > >
> o_linux_515_my_brightness%2F&amp;data=04%7C01%7CRoman.Li%40amd.co
> m%7
> > >
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> 83d
> > >
> %7C0%7C0%7C637726663861883494%7CUnknown%7CTWFpbGZsb3d8eyJWIjoi
> MC4wLj
> > >
> AwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;s
> dat
> > >
> a=hfsaEzng9%2FjAI2F%2BKg87Tv2Mu%2FfPurCQELr62%2B%2FVF%2BQ%3D&a
> mp;res
> > > erved=0