AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

[Walt Holman]

Hello,

With the latest drm fixes this week on 6.16-rc2, I am experiencing a
black screen instead of the sddm greeter and the GPU appears to be
locked up. I can ssh into the laptop and reboot it, but that's about
it. I have bisected the commit to commit id:
16dc8bc27c2aa3c93905d3e885e27f1e3535f09a and upon reverting the
commit, the system works as normal. The hardware is an Asus Rog
Zephyrus G16 with AMD Ryzen AI 9 HX 370 w/ Radeon 890M video. I'm able
to test patches etc.. if need be.

16dc8bc27c2aa3c93905d3e885e27f1e3535f09a is the first bad commit
commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a (HEAD)
Author: Mario Limonciello <mario.limonciello@amd.com>
Date:   Thu May 29 09:46:32 2025 -0500

    drm/amd/display: Export full brightness range to userspace

    [WHY]
    Userspace currently is offered a range from 0-0xFF but the PWM is
    programmed from 0-0xFFFF.  This can be limiting to some software
    that wants to apply greater granularity.

    [HOW]
    Convert internally to firmware values only when mapping custom
    brightness curves because these are in 0-0xFF range. Advertise full
    PWM range to userspace.

    Cc: Mario Limonciello <mario.limonciello@amd.com>
    Cc: Alex Deucher <alexander.deucher@amd.com>
    Reviewed-by: Roman Li <roman.li@amd.com>
    Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
    Signed-off-by: Alex Hung <alex.hung@amd.com>
    Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
    (cherry picked from commit 8dbd72cb790058ce52279af38a43c2b302fdd3e5)
    Cc: stable@vger.kernel.org

 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 41
+++++++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 14 deletions(-)

Re: AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

[Mario Limonciello]

On 6/21/25 10:18 AM, Walt Holman wrote:
> Hello,
> 
> With the latest drm fixes this week on 6.16-rc2, I am experiencing a
> black screen instead of the sddm greeter and the GPU appears to be
> locked up. I can ssh into the laptop and reboot it, but that's about
> it. I have bisected the commit to commit id:
> 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a and upon reverting the
> commit, the system works as normal. The hardware is an Asus Rog
> Zephyrus G16 with AMD Ryzen AI 9 HX 370 w/ Radeon 890M video. I'm able
> to test patches etc.. if need be.

Hi there,

By chance do you have an OLED panel?  If so can you please try the patch 
attached to this bug?

https://gitlab.freedesktop.org/drm/amd/-/issues/4338

Thanks,

> 
> 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a is the first bad commit
> commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a (HEAD)
> Author: Mario Limonciello <mario.limonciello@amd.com>
> Date:   Thu May 29 09:46:32 2025 -0500
> 
>      drm/amd/display: Export full brightness range to userspace
> 
>      [WHY]
>      Userspace currently is offered a range from 0-0xFF but the PWM is
>      programmed from 0-0xFFFF.  This can be limiting to some software
>      that wants to apply greater granularity.
> 
>      [HOW]
>      Convert internally to firmware values only when mapping custom
>      brightness curves because these are in 0-0xFF range. Advertise full
>      PWM range to userspace.
> 
>      Cc: Mario Limonciello <mario.limonciello@amd.com>
>      Cc: Alex Deucher <alexander.deucher@amd.com>
>      Reviewed-by: Roman Li <roman.li@amd.com>
>      Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>      Signed-off-by: Alex Hung <alex.hung@amd.com>
>      Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
>      Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
>      (cherry picked from commit 8dbd72cb790058ce52279af38a43c2b302fdd3e5)
>      Cc: stable@vger.kernel.org
> 
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 41
> +++++++++++++++++++++++++++--------------
>   1 file changed, 27 insertions(+), 14 deletions(-)
> 

Re: AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

[Walt Holman]

On Sat, Jun 21, 2025 at 10:52 AM Mario Limonciello <superm1@kernel.org> wrote:
>
>
>
> On 6/21/25 10:18 AM, Walt Holman wrote:
> > Hello,
> >
> > With the latest drm fixes this week on 6.16-rc2, I am experiencing a
> > black screen instead of the sddm greeter and the GPU appears to be
> > locked up. I can ssh into the laptop and reboot it, but that's about
> > it. I have bisected the commit to commit id:
> > 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a and upon reverting the
> > commit, the system works as normal. The hardware is an Asus Rog
> > Zephyrus G16 with AMD Ryzen AI 9 HX 370 w/ Radeon 890M video. I'm able
> > to test patches etc.. if need be.
>
> Hi there,
>
> By chance do you have an OLED panel?  If so can you please try the patch
> attached to this bug?
>
> https://gitlab.freedesktop.org/drm/amd/-/issues/4338
>
> Thanks,
>
> >
> > 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a is the first bad commit
> > commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a (HEAD)
> > Author: Mario Limonciello <mario.limonciello@amd.com>
> > Date:   Thu May 29 09:46:32 2025 -0500
> >
> >      drm/amd/display: Export full brightness range to userspace
> >
> >      [WHY]
> >      Userspace currently is offered a range from 0-0xFF but the PWM is
> >      programmed from 0-0xFFFF.  This can be limiting to some software
> >      that wants to apply greater granularity.
> >
> >      [HOW]
> >      Convert internally to firmware values only when mapping custom
> >      brightness curves because these are in 0-0xFF range. Advertise full
> >      PWM range to userspace.
> >
> >      Cc: Mario Limonciello <mario.limonciello@amd.com>
> >      Cc: Alex Deucher <alexander.deucher@amd.com>
> >      Reviewed-by: Roman Li <roman.li@amd.com>
> >      Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> >      Signed-off-by: Alex Hung <alex.hung@amd.com>
> >      Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
> >      Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> >      (cherry picked from commit 8dbd72cb790058ce52279af38a43c2b302fdd3e5)
> >      Cc: stable@vger.kernel.org
> >
> >   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 41
> > +++++++++++++++++++++++++++--------------
> >   1 file changed, 27 insertions(+), 14 deletions(-)
> >
>

Yes, I do have an OLED panel and that patch does make it visible
again. It is still very dark, but visible.

-Walt

Re: AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

[Walt Holman]

On Sat, Jun 21, 2025 at 11:03 AM Walt Holman <waltholman09@gmail.com> wrote:
>
> On Sat, Jun 21, 2025 at 10:52 AM Mario Limonciello <superm1@kernel.org> wrote:
> >
> >
> >
> > On 6/21/25 10:18 AM, Walt Holman wrote:
> > > Hello,
> > >
> > > With the latest drm fixes this week on 6.16-rc2, I am experiencing a
> > > black screen instead of the sddm greeter and the GPU appears to be
> > > locked up. I can ssh into the laptop and reboot it, but that's about
> > > it. I have bisected the commit to commit id:
> > > 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a and upon reverting the
> > > commit, the system works as normal. The hardware is an Asus Rog
> > > Zephyrus G16 with AMD Ryzen AI 9 HX 370 w/ Radeon 890M video. I'm able
> > > to test patches etc.. if need be.
> >
> > Hi there,
> >
> > By chance do you have an OLED panel?  If so can you please try the patch
> > attached to this bug?
> >
> > https://gitlab.freedesktop.org/drm/amd/-/issues/4338
> >
> > Thanks,
> >
> > >
> > > 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a is the first bad commit
> > > commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a (HEAD)
> > > Author: Mario Limonciello <mario.limonciello@amd.com>
> > > Date:   Thu May 29 09:46:32 2025 -0500
> > >
> > >      drm/amd/display: Export full brightness range to userspace
> > >
> > >      [WHY]
> > >      Userspace currently is offered a range from 0-0xFF but the PWM is
> > >      programmed from 0-0xFFFF.  This can be limiting to some software
> > >      that wants to apply greater granularity.
> > >
> > >      [HOW]
> > >      Convert internally to firmware values only when mapping custom
> > >      brightness curves because these are in 0-0xFF range. Advertise full
> > >      PWM range to userspace.
> > >
> > >      Cc: Mario Limonciello <mario.limonciello@amd.com>
> > >      Cc: Alex Deucher <alexander.deucher@amd.com>
> > >      Reviewed-by: Roman Li <roman.li@amd.com>
> > >      Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> > >      Signed-off-by: Alex Hung <alex.hung@amd.com>
> > >      Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
> > >      Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> > >      (cherry picked from commit 8dbd72cb790058ce52279af38a43c2b302fdd3e5)
> > >      Cc: stable@vger.kernel.org
> > >
> > >   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 41
> > > +++++++++++++++++++++++++++--------------
> > >   1 file changed, 27 insertions(+), 14 deletions(-)
> > >
> >
>
> Yes, I do have an OLED panel and that patch does make it visible
> again. It is still very dark, but visible.
>
> -Walt

Upon rebooting again, the display was much brighter and is fine. Just
the first boot after that was dark.

-Walt

Re: AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

[Mario Limonciello]

On 6/21/25 11:07 AM, Walt Holman wrote:
> On Sat, Jun 21, 2025 at 11:03 AM Walt Holman <waltholman09@gmail.com> wrote:
>>
>> On Sat, Jun 21, 2025 at 10:52 AM Mario Limonciello <superm1@kernel.org> wrote:
>>>
>>>
>>>
>>> On 6/21/25 10:18 AM, Walt Holman wrote:
>>>> Hello,
>>>>
>>>> With the latest drm fixes this week on 6.16-rc2, I am experiencing a
>>>> black screen instead of the sddm greeter and the GPU appears to be
>>>> locked up. I can ssh into the laptop and reboot it, but that's about
>>>> it. I have bisected the commit to commit id:
>>>> 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a and upon reverting the
>>>> commit, the system works as normal. The hardware is an Asus Rog
>>>> Zephyrus G16 with AMD Ryzen AI 9 HX 370 w/ Radeon 890M video. I'm able
>>>> to test patches etc.. if need be.
>>>
>>> Hi there,
>>>
>>> By chance do you have an OLED panel?  If so can you please try the patch
>>> attached to this bug?
>>>
>>> https://gitlab.freedesktop.org/drm/amd/-/issues/4338
>>>
>>> Thanks,
>>>
>>>>
>>>> 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a is the first bad commit
>>>> commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a (HEAD)
>>>> Author: Mario Limonciello <mario.limonciello@amd.com>
>>>> Date:   Thu May 29 09:46:32 2025 -0500
>>>>
>>>>       drm/amd/display: Export full brightness range to userspace
>>>>
>>>>       [WHY]
>>>>       Userspace currently is offered a range from 0-0xFF but the PWM is
>>>>       programmed from 0-0xFFFF.  This can be limiting to some software
>>>>       that wants to apply greater granularity.
>>>>
>>>>       [HOW]
>>>>       Convert internally to firmware values only when mapping custom
>>>>       brightness curves because these are in 0-0xFF range. Advertise full
>>>>       PWM range to userspace.
>>>>
>>>>       Cc: Mario Limonciello <mario.limonciello@amd.com>
>>>>       Cc: Alex Deucher <alexander.deucher@amd.com>
>>>>       Reviewed-by: Roman Li <roman.li@amd.com>
>>>>       Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>>>>       Signed-off-by: Alex Hung <alex.hung@amd.com>
>>>>       Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
>>>>       Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
>>>>       (cherry picked from commit 8dbd72cb790058ce52279af38a43c2b302fdd3e5)
>>>>       Cc: stable@vger.kernel.org
>>>>
>>>>    drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 41
>>>> +++++++++++++++++++++++++++--------------
>>>>    1 file changed, 27 insertions(+), 14 deletions(-)
>>>>
>>>
>>
>> Yes, I do have an OLED panel and that patch does make it visible
>> again. It is still very dark, but visible.
>>
>> -Walt
> 
> Upon rebooting again, the display was much brighter and is fine. Just
> the first boot after that was dark.
> 
> -Walt

Thanks, this makes sense.  I suspect that because 0 means "off" for your 
panel that the patch you bisected to exposed running at 0 (or near 
enough to 0) that it caused this behavior.

That patch you tested will be upstreamed in a future promotion, and I 
think we can take it in a -fixes PR later in the 6.16 fixes cycle.

But there is one more thing I would like to confirm - on your system can 
you run with drm.debug=0x106 on the kernel command line and share me the 
output from this debug print?

https://github.com/torvalds/linux/blob/v6.16-rc2/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c#L4933

Re: AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

[Walt Holman]

[-- Attachment #1: Type: text/plain, Size: 3840 bytes --]

On Sat, Jun 21, 2025 at 2:12 PM Mario Limonciello <superm1@kernel.org> wrote:
>
>
>
> On 6/21/25 11:07 AM, Walt Holman wrote:
> > On Sat, Jun 21, 2025 at 11:03 AM Walt Holman <waltholman09@gmail.com> wrote:
> >>
> >> On Sat, Jun 21, 2025 at 10:52 AM Mario Limonciello <superm1@kernel.org> wrote:
> >>>
> >>>
> >>>
> >>> On 6/21/25 10:18 AM, Walt Holman wrote:
> >>>> Hello,
> >>>>
> >>>> With the latest drm fixes this week on 6.16-rc2, I am experiencing a
> >>>> black screen instead of the sddm greeter and the GPU appears to be
> >>>> locked up. I can ssh into the laptop and reboot it, but that's about
> >>>> it. I have bisected the commit to commit id:
> >>>> 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a and upon reverting the
> >>>> commit, the system works as normal. The hardware is an Asus Rog
> >>>> Zephyrus G16 with AMD Ryzen AI 9 HX 370 w/ Radeon 890M video. I'm able
> >>>> to test patches etc.. if need be.
> >>>
> >>> Hi there,
> >>>
> >>> By chance do you have an OLED panel?  If so can you please try the patch
> >>> attached to this bug?
> >>>
> >>> https://gitlab.freedesktop.org/drm/amd/-/issues/4338
> >>>
> >>> Thanks,
> >>>
> >>>>
> >>>> 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a is the first bad commit
> >>>> commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a (HEAD)
> >>>> Author: Mario Limonciello <mario.limonciello@amd.com>
> >>>> Date:   Thu May 29 09:46:32 2025 -0500
> >>>>
> >>>>       drm/amd/display: Export full brightness range to userspace
> >>>>
> >>>>       [WHY]
> >>>>       Userspace currently is offered a range from 0-0xFF but the PWM is
> >>>>       programmed from 0-0xFFFF.  This can be limiting to some software
> >>>>       that wants to apply greater granularity.
> >>>>
> >>>>       [HOW]
> >>>>       Convert internally to firmware values only when mapping custom
> >>>>       brightness curves because these are in 0-0xFF range. Advertise full
> >>>>       PWM range to userspace.
> >>>>
> >>>>       Cc: Mario Limonciello <mario.limonciello@amd.com>
> >>>>       Cc: Alex Deucher <alexander.deucher@amd.com>
> >>>>       Reviewed-by: Roman Li <roman.li@amd.com>
> >>>>       Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> >>>>       Signed-off-by: Alex Hung <alex.hung@amd.com>
> >>>>       Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
> >>>>       Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> >>>>       (cherry picked from commit 8dbd72cb790058ce52279af38a43c2b302fdd3e5)
> >>>>       Cc: stable@vger.kernel.org
> >>>>
> >>>>    drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 41
> >>>> +++++++++++++++++++++++++++--------------
> >>>>    1 file changed, 27 insertions(+), 14 deletions(-)
> >>>>
> >>>
> >>
> >> Yes, I do have an OLED panel and that patch does make it visible
> >> again. It is still very dark, but visible.
> >>
> >> -Walt
> >
> > Upon rebooting again, the display was much brighter and is fine. Just
> > the first boot after that was dark.
> >
> > -Walt
>
> Thanks, this makes sense.  I suspect that because 0 means "off" for your
> panel that the patch you bisected to exposed running at 0 (or near
> enough to 0) that it caused this behavior.
>
> That patch you tested will be upstreamed in a future promotion, and I
> think we can take it in a -fixes PR later in the 6.16 fixes cycle.
>
> But there is one more thing I would like to confirm - on your system can
> you run with drm.debug=0x106 on the kernel command line and share me the
> output from this debug print?
>
> https://github.com/torvalds/linux/blob/v6.16-rc2/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c#L4933
>
>
>
Hopefully, this is what you need. I grepped dmesg for drm and threw it
into this file attached. Let me know if you need anything else.

-Walt

[-- Attachment #2: drm-output-logs.txt.gz --]
[-- Type: application/gzip, Size: 19638 bytes --]

Re: AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

[Mario Limonciello]

On 6/21/25 2:32 PM, Walt Holman wrote:
> On Sat, Jun 21, 2025 at 2:12 PM Mario Limonciello <superm1@kernel.org> wrote:
>>
>>
>>
>> On 6/21/25 11:07 AM, Walt Holman wrote:
>>> On Sat, Jun 21, 2025 at 11:03 AM Walt Holman <waltholman09@gmail.com> wrote:
>>>>
>>>> On Sat, Jun 21, 2025 at 10:52 AM Mario Limonciello <superm1@kernel.org> wrote:
>>>>>
>>>>>
>>>>>
>>>>> On 6/21/25 10:18 AM, Walt Holman wrote:
>>>>>> Hello,
>>>>>>
>>>>>> With the latest drm fixes this week on 6.16-rc2, I am experiencing a
>>>>>> black screen instead of the sddm greeter and the GPU appears to be
>>>>>> locked up. I can ssh into the laptop and reboot it, but that's about
>>>>>> it. I have bisected the commit to commit id:
>>>>>> 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a and upon reverting the
>>>>>> commit, the system works as normal. The hardware is an Asus Rog
>>>>>> Zephyrus G16 with AMD Ryzen AI 9 HX 370 w/ Radeon 890M video. I'm able
>>>>>> to test patches etc.. if need be.
>>>>>
>>>>> Hi there,
>>>>>
>>>>> By chance do you have an OLED panel?  If so can you please try the patch
>>>>> attached to this bug?
>>>>>
>>>>> https://gitlab.freedesktop.org/drm/amd/-/issues/4338
>>>>>
>>>>> Thanks,
>>>>>
>>>>>>
>>>>>> 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a is the first bad commit
>>>>>> commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a (HEAD)
>>>>>> Author: Mario Limonciello <mario.limonciello@amd.com>
>>>>>> Date:   Thu May 29 09:46:32 2025 -0500
>>>>>>
>>>>>>        drm/amd/display: Export full brightness range to userspace
>>>>>>
>>>>>>        [WHY]
>>>>>>        Userspace currently is offered a range from 0-0xFF but the PWM is
>>>>>>        programmed from 0-0xFFFF.  This can be limiting to some software
>>>>>>        that wants to apply greater granularity.
>>>>>>
>>>>>>        [HOW]
>>>>>>        Convert internally to firmware values only when mapping custom
>>>>>>        brightness curves because these are in 0-0xFF range. Advertise full
>>>>>>        PWM range to userspace.
>>>>>>
>>>>>>        Cc: Mario Limonciello <mario.limonciello@amd.com>
>>>>>>        Cc: Alex Deucher <alexander.deucher@amd.com>
>>>>>>        Reviewed-by: Roman Li <roman.li@amd.com>
>>>>>>        Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>>>>>>        Signed-off-by: Alex Hung <alex.hung@amd.com>
>>>>>>        Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
>>>>>>        Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
>>>>>>        (cherry picked from commit 8dbd72cb790058ce52279af38a43c2b302fdd3e5)
>>>>>>        Cc: stable@vger.kernel.org
>>>>>>
>>>>>>     drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 41
>>>>>> +++++++++++++++++++++++++++--------------
>>>>>>     1 file changed, 27 insertions(+), 14 deletions(-)
>>>>>>
>>>>>
>>>>
>>>> Yes, I do have an OLED panel and that patch does make it visible
>>>> again. It is still very dark, but visible.
>>>>
>>>> -Walt
>>>
>>> Upon rebooting again, the display was much brighter and is fine. Just
>>> the first boot after that was dark.
>>>
>>> -Walt
>>
>> Thanks, this makes sense.  I suspect that because 0 means "off" for your
>> panel that the patch you bisected to exposed running at 0 (or near
>> enough to 0) that it caused this behavior.
>>
>> That patch you tested will be upstreamed in a future promotion, and I
>> think we can take it in a -fixes PR later in the 6.16 fixes cycle.
>>
>> But there is one more thing I would like to confirm - on your system can
>> you run with drm.debug=0x106 on the kernel command line and share me the
>> output from this debug print?
>>
>> https://github.com/torvalds/linux/blob/v6.16-rc2/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c#L4933
>>
>>
>>
> Hopefully, this is what you need. I grepped dmesg for drm and threw it
> into this file attached. Let me know if you need anything else.
> 
> -Walt

Thanks I see another problem.  Can you add this patch?

https://lore.kernel.org/amd-gfx/20250623144821.745908-1-mario.limonciello@amd.com/T/#u

Thanks,

Re: AMDGPU - Regression: Black screen due to commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a

[Walt Holman]

On Mon, Jun 23, 2025 at 9:51 AM Mario Limonciello <superm1@kernel.org> wrote:
>
> On 6/21/25 2:32 PM, Walt Holman wrote:
> > On Sat, Jun 21, 2025 at 2:12 PM Mario Limonciello <superm1@kernel.org> wrote:
> >>
> >>
> >>
> >> On 6/21/25 11:07 AM, Walt Holman wrote:
> >>> On Sat, Jun 21, 2025 at 11:03 AM Walt Holman <waltholman09@gmail.com> wrote:
> >>>>
> >>>> On Sat, Jun 21, 2025 at 10:52 AM Mario Limonciello <superm1@kernel.org> wrote:
> >>>>>
> >>>>>
> >>>>>
> >>>>> On 6/21/25 10:18 AM, Walt Holman wrote:
> >>>>>> Hello,
> >>>>>>
> >>>>>> With the latest drm fixes this week on 6.16-rc2, I am experiencing a
> >>>>>> black screen instead of the sddm greeter and the GPU appears to be
> >>>>>> locked up. I can ssh into the laptop and reboot it, but that's about
> >>>>>> it. I have bisected the commit to commit id:
> >>>>>> 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a and upon reverting the
> >>>>>> commit, the system works as normal. The hardware is an Asus Rog
> >>>>>> Zephyrus G16 with AMD Ryzen AI 9 HX 370 w/ Radeon 890M video. I'm able
> >>>>>> to test patches etc.. if need be.
> >>>>>
> >>>>> Hi there,
> >>>>>
> >>>>> By chance do you have an OLED panel?  If so can you please try the patch
> >>>>> attached to this bug?
> >>>>>
> >>>>> https://gitlab.freedesktop.org/drm/amd/-/issues/4338
> >>>>>
> >>>>> Thanks,
> >>>>>
> >>>>>>
> >>>>>> 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a is the first bad commit
> >>>>>> commit 16dc8bc27c2aa3c93905d3e885e27f1e3535f09a (HEAD)
> >>>>>> Author: Mario Limonciello <mario.limonciello@amd.com>
> >>>>>> Date:   Thu May 29 09:46:32 2025 -0500
> >>>>>>
> >>>>>>        drm/amd/display: Export full brightness range to userspace
> >>>>>>
> >>>>>>        [WHY]
> >>>>>>        Userspace currently is offered a range from 0-0xFF but the PWM is
> >>>>>>        programmed from 0-0xFFFF.  This can be limiting to some software
> >>>>>>        that wants to apply greater granularity.
> >>>>>>
> >>>>>>        [HOW]
> >>>>>>        Convert internally to firmware values only when mapping custom
> >>>>>>        brightness curves because these are in 0-0xFF range. Advertise full
> >>>>>>        PWM range to userspace.
> >>>>>>
> >>>>>>        Cc: Mario Limonciello <mario.limonciello@amd.com>
> >>>>>>        Cc: Alex Deucher <alexander.deucher@amd.com>
> >>>>>>        Reviewed-by: Roman Li <roman.li@amd.com>
> >>>>>>        Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> >>>>>>        Signed-off-by: Alex Hung <alex.hung@amd.com>
> >>>>>>        Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
> >>>>>>        Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> >>>>>>        (cherry picked from commit 8dbd72cb790058ce52279af38a43c2b302fdd3e5)
> >>>>>>        Cc: stable@vger.kernel.org
> >>>>>>
> >>>>>>     drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 41
> >>>>>> +++++++++++++++++++++++++++--------------
> >>>>>>     1 file changed, 27 insertions(+), 14 deletions(-)
> >>>>>>
> >>>>>
> >>>>
> >>>> Yes, I do have an OLED panel and that patch does make it visible
> >>>> again. It is still very dark, but visible.
> >>>>
> >>>> -Walt
> >>>
> >>> Upon rebooting again, the display was much brighter and is fine. Just
> >>> the first boot after that was dark.
> >>>
> >>> -Walt
> >>
> >> Thanks, this makes sense.  I suspect that because 0 means "off" for your
> >> panel that the patch you bisected to exposed running at 0 (or near
> >> enough to 0) that it caused this behavior.
> >>
> >> That patch you tested will be upstreamed in a future promotion, and I
> >> think we can take it in a -fixes PR later in the 6.16 fixes cycle.
> >>
> >> But there is one more thing I would like to confirm - on your system can
> >> you run with drm.debug=0x106 on the kernel command line and share me the
> >> output from this debug print?
> >>
> >> https://github.com/torvalds/linux/blob/v6.16-rc2/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c#L4933
> >>
> >>
> >>
> > Hopefully, this is what you need. I grepped dmesg for drm and threw it
> > into this file attached. Let me know if you need anything else.
> >
> > -Walt
>
> Thanks I see another problem.  Can you add this patch?
>
> https://lore.kernel.org/amd-gfx/20250623144821.745908-1-mario.limonciello@amd.com/T/#u
>
> Thanks,

Got it added. Can't say that I notice a big difference, however, the
login screen may have been a tad brighter. But it's obviously more
correct now. Thanks,

-Walt