[v3,0/2] drm: minimum backlight overrides and implementation for amdgpu

Message

Thomas Weißschuh July 31, 2024, 5 p.m. UTC

The value of "min_input_signal" returned from ATIF on a Framework AMD 13
is "12". This leads to a fairly bright minimum display backlight.

Add a generic override helper for the user to override the settings
provided by the firmware through the kernel cmdline.
Also add amdgpu as a user of that helper.

One solution would be a fixed firmware version, which was announced but
has no timeline.

This helper does conflict with the mode override via the cmdline.
Only one can be specified.
IMO the mode override can be extended to also handle "min-brightness"
when that becomes necessary.

---
Changes in v3:
- Switch to cmdline override parameter
- Link to v2: https://lore.kernel.org/r/[e-mail]

Changes in v2:
- Introduce proper drm backlight quirk infrastructure
- Quirk by EDID and DMI instead of only DMI
- Limit quirk to only single Framework 13 matte panel
- Link to v1: https://lore.kernel.org/r/[e-mail]

---
Thomas Weißschuh (2):
      drm/connector: add drm_connector_get_cmdline_min_brightness_override()
      drm/amd/display: implement minimum brightness override

 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  6 ++++
 drivers/gpu/drm/drm_connector.c                   | 34 +++++++++++++++++++++++
 include/drm/drm_connector.h                       |  2 ++
 3 files changed, 42 insertions(+)
---
base-commit: 36821612eb3091a21f7f4a907b497064725080c3
change-id: 20240610-amdgpu-min-backlight-quirk-8402fd8e736a

Best regards,

Comments

Jani Nikula July 31, 2024, 5:40 p.m. UTC | #1

On Wed, 31 Jul 2024, Thomas Weißschuh <[e-mail]> wrote:
> The value of "min_input_signal" returned from ATIF on a Framework AMD 13
> is "12". This leads to a fairly bright minimum display backlight.
>
> Add a generic override helper for the user to override the settings
> provided by the firmware through the kernel cmdline.
> Also add amdgpu as a user of that helper.
>
> One solution would be a fixed firmware version, which was announced but
> has no timeline.

The flip side is that if we add this now, it pretty much has a timeline:
We'll have to carry and support it forever.

It's not a great prospect for something so specific. Not to mention that
the limits are generally there for electrical minimums that should not
be overridden. And before you know it, we'll have bug reports about
flickering screens...

BR,
Jani.


>
> This helper does conflict with the mode override via the cmdline.
> Only one can be specified.
> IMO the mode override can be extended to also handle "min-brightness"
> when that becomes necessary.
>
> ---
> Changes in v3:
> - Switch to cmdline override parameter
> - Link to v2: https://lore.kernel.org/r/[e-mail]
>
> Changes in v2:
> - Introduce proper drm backlight quirk infrastructure
> - Quirk by EDID and DMI instead of only DMI
> - Limit quirk to only single Framework 13 matte panel
> - Link to v1: https://lore.kernel.org/r/[e-mail]
>
> ---
> Thomas Weißschuh (2):
>       drm/connector: add drm_connector_get_cmdline_min_brightness_override()
>       drm/amd/display: implement minimum brightness override
>
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  6 ++++
>  drivers/gpu/drm/drm_connector.c                   | 34 +++++++++++++++++++++++
>  include/drm/drm_connector.h                       |  2 ++
>  3 files changed, 42 insertions(+)
> ---
> base-commit: 36821612eb3091a21f7f4a907b497064725080c3
> change-id: 20240610-amdgpu-min-backlight-quirk-8402fd8e736a
>
> Best regards,

Daniel Vetter July 31, 2024, 8:55 p.m. UTC | #2

On Wed, Jul 31, 2024 at 08:40:12PM +0300, Jani Nikula wrote:
> On Wed, 31 Jul 2024, Thomas Weißschuh <[e-mail]> wrote:
> > The value of "min_input_signal" returned from ATIF on a Framework AMD 13
> > is "12". This leads to a fairly bright minimum display backlight.
> >
> > Add a generic override helper for the user to override the settings
> > provided by the firmware through the kernel cmdline.
> > Also add amdgpu as a user of that helper.
> >
> > One solution would be a fixed firmware version, which was announced but
> > has no timeline.
> 
> The flip side is that if we add this now, it pretty much has a timeline:
> We'll have to carry and support it forever.
> 
> It's not a great prospect for something so specific. Not to mention that
> the limits are generally there for electrical minimums that should not
> be overridden. And before you know it, we'll have bug reports about
> flickering screens...

Yeah I think for this specific case where a fixed firmware is already
kinda promised, a quirk is the right fix. Otherwise we open up a can of
worms here ... so personally I like v2 a lot more.
-Sima

> 
> BR,
> Jani.
> 
> 
> >
> > This helper does conflict with the mode override via the cmdline.
> > Only one can be specified.
> > IMO the mode override can be extended to also handle "min-brightness"
> > when that becomes necessary.
> >
> > ---
> > Changes in v3:
> > - Switch to cmdline override parameter
> > - Link to v2: https://lore.kernel.org/r/[e-mail]
> >
> > Changes in v2:
> > - Introduce proper drm backlight quirk infrastructure
> > - Quirk by EDID and DMI instead of only DMI
> > - Limit quirk to only single Framework 13 matte panel
> > - Link to v1: https://lore.kernel.org/r/[e-mail]
> >
> > ---
> > Thomas Weißschuh (2):
> >       drm/connector: add drm_connector_get_cmdline_min_brightness_override()
> >       drm/amd/display: implement minimum brightness override
> >
> >  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  6 ++++
> >  drivers/gpu/drm/drm_connector.c                   | 34 +++++++++++++++++++++++
> >  include/drm/drm_connector.h                       |  2 ++
> >  3 files changed, 42 insertions(+)
> > ---
> > base-commit: 36821612eb3091a21f7f4a907b497064725080c3
> > change-id: 20240610-amdgpu-min-backlight-quirk-8402fd8e736a
> >
> > Best regards,
> 
> -- 
> Jani Nikula, Intel

Hans de Goede Aug. 1, 2024, 8:52 a.m. UTC | #3

Hi,

On 7/31/24 10:55 PM, Daniel Vetter wrote:
> On Wed, Jul 31, 2024 at 08:40:12PM +0300, Jani Nikula wrote:
>> On Wed, 31 Jul 2024, Thomas Weißschuh <[e-mail]> wrote:
>>> The value of "min_input_signal" returned from ATIF on a Framework AMD 13
>>> is "12". This leads to a fairly bright minimum display backlight.
>>>
>>> Add a generic override helper for the user to override the settings
>>> provided by the firmware through the kernel cmdline.
>>> Also add amdgpu as a user of that helper.
>>>
>>> One solution would be a fixed firmware version, which was announced but
>>> has no timeline.
>>
>> The flip side is that if we add this now, it pretty much has a timeline:
>> We'll have to carry and support it forever.
>>
>> It's not a great prospect for something so specific. Not to mention that
>> the limits are generally there for electrical minimums that should not
>> be overridden. And before you know it, we'll have bug reports about
>> flickering screens...
> 
> Yeah I think for this specific case where a fixed firmware is already
> kinda promised, a quirk is the right fix. Otherwise we open up a can of
> worms here ... so personally I like v2 a lot more.
> -Sima

Ok, with both Jani and Sima preferring the quirk approach from v2,
I withdraw my objection against v2. So lets go with that version.

Thomas, sorry about this.

I see that other then a remark from Jeff Johnson about a missing
MODULE_DESCRIPTION() v2 does not have any reviews yet though.

So we will need to review that version now. Might be best for
visibility of the patches in people's review queue to repost
v2 as v4 with the MODULE_DESCRIPTION() fixed ?

Regards,

Hans



>>> This helper does conflict with the mode override via the cmdline.
>>> Only one can be specified.
>>> IMO the mode override can be extended to also handle "min-brightness"
>>> when that becomes necessary.
>>>
>>> ---
>>> Changes in v3:
>>> - Switch to cmdline override parameter
>>> - Link to v2: https://lore.kernel.org/r/[e-mail]
>>>
>>> Changes in v2:
>>> - Introduce proper drm backlight quirk infrastructure
>>> - Quirk by EDID and DMI instead of only DMI
>>> - Limit quirk to only single Framework 13 matte panel
>>> - Link to v1: https://lore.kernel.org/r/[e-mail]
>>>
>>> ---
>>> Thomas Weißschuh (2):
>>>       drm/connector: add drm_connector_get_cmdline_min_brightness_override()
>>>       drm/amd/display: implement minimum brightness override
>>>
>>>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  6 ++++
>>>  drivers/gpu/drm/drm_connector.c                   | 34 +++++++++++++++++++++++
>>>  include/drm/drm_connector.h                       |  2 ++
>>>  3 files changed, 42 insertions(+)
>>> ---
>>> base-commit: 36821612eb3091a21f7f4a907b497064725080c3
>>> change-id: 20240610-amdgpu-min-backlight-quirk-8402fd8e736a
>>>
>>> Best regards,
>>
>> -- 
>> Jani Nikula, Intel
>

Thomas Weißschuh Aug. 2, 2024, 3:53 p.m. UTC | #4

Hi,

On 2024-08-01 10:52:55+0000, Hans de Goede wrote:
> On 7/31/24 10:55 PM, Daniel Vetter wrote:
> > On Wed, Jul 31, 2024 at 08:40:12PM +0300, Jani Nikula wrote:
> >> On Wed, 31 Jul 2024, Thomas Weißschuh <[e-mail]> wrote:
> >>> The value of "min_input_signal" returned from ATIF on a Framework AMD 13
> >>> is "12". This leads to a fairly bright minimum display backlight.
> >>>
> >>> Add a generic override helper for the user to override the settings
> >>> provided by the firmware through the kernel cmdline.
> >>> Also add amdgpu as a user of that helper.
> >>>
> >>> One solution would be a fixed firmware version, which was announced but
> >>> has no timeline.
> >>
> >> The flip side is that if we add this now, it pretty much has a timeline:
> >> We'll have to carry and support it forever.
> >>
> >> It's not a great prospect for something so specific. Not to mention that
> >> the limits are generally there for electrical minimums that should not
> >> be overridden. And before you know it, we'll have bug reports about
> >> flickering screens...
> > 
> > Yeah I think for this specific case where a fixed firmware is already
> > kinda promised, a quirk is the right fix. Otherwise we open up a can of
> > worms here ... so personally I like v2 a lot more.
> > -Sima
> 
> Ok, with both Jani and Sima preferring the quirk approach from v2,
> I withdraw my objection against v2. So lets go with that version.

Ack.

I want to note though, that there are enough other commandline
options that can mess things up.
An invalid video=MODELINE, custom ACPI tables, etc, so the fallout from the
new commandline variable doesn't seem too bad to me.

> Thomas, sorry about this.

No worries!

> I see that other then a remark from Jeff Johnson about a missing
> MODULE_DESCRIPTION() v2 does not have any reviews yet though.
> 
> So we will need to review that version now. Might be best for
> visibility of the patches in people's review queue to repost
> v2 as v4 with the MODULE_DESCRIPTION() fixed ?

I can do that.

> 
> >>> This helper does conflict with the mode override via the cmdline.
> >>> Only one can be specified.
> >>> IMO the mode override can be extended to also handle "min-brightness"
> >>> when that becomes necessary.
> >>>
> >>> ---
> >>> Changes in v3:
> >>> - Switch to cmdline override parameter
> >>> - Link to v2: https://lore.kernel.org/r/[e-mail]
> >>>
> >>> Changes in v2:
> >>> - Introduce proper drm backlight quirk infrastructure
> >>> - Quirk by EDID and DMI instead of only DMI
> >>> - Limit quirk to only single Framework 13 matte panel
> >>> - Link to v1: https://lore.kernel.org/r/[e-mail]
> >>>
> >>> ---
> >>> Thomas Weißschuh (2):
> >>>       drm/connector: add drm_connector_get_cmdline_min_brightness_override()
> >>>       drm/amd/display: implement minimum brightness override
> >>>
> >>>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  6 ++++
> >>>  drivers/gpu/drm/drm_connector.c                   | 34 +++++++++++++++++++++++
> >>>  include/drm/drm_connector.h                       |  2 ++
> >>>  3 files changed, 42 insertions(+)
> >>> ---
> >>> base-commit: 36821612eb3091a21f7f4a907b497064725080c3
> >>> change-id: 20240610-amdgpu-min-backlight-quirk-8402fd8e736a
> >>>
> >>> Best regards,
> >>
> >> -- 
> >> Jani Nikula, Intel
> > 
>