diff mbox series

[v3] ACPI: video: Put ACPI video and its child devices to D0 at boot

Message ID 20230721152143.3108017-1-kai.heng.feng@canonical.com
State Accepted
Commit 89c290ea758911e660878e26270e084d862c03b0
Headers show
Series [v3] ACPI: video: Put ACPI video and its child devices to D0 at boot | expand

Commit Message

Kai-Heng Feng July 21, 2023, 3:21 p.m. UTC 
Screen brightness can only be changed once on HP ZBook Fury 16 G10.

Vendor identified the root cause as Linux doesn't invoke _PS0 at boot
for all ACPI devices:

    Scope (\_SB.PC00.GFX0)
    {
        Scope (DD1F)
        {
            Method (_PS0, 0, Serialized)  // _PS0: Power State 0
            {
                If (CondRefOf (\_SB.PC00.LPCB.EC0.SSBC))
                {
                    \_SB.PC00.LPCB.EC0.SSBC ()
                }
            }
	    ...
	}
	...
    }

The \_SB.PC00.GFX0.DD1F is the panel device, and its _PS0 needs to be
executed to make the brightness control work properly.

_PS0 doesn't get invoked for this device because _PSC is missing,
which violates ACPI spec 6.3, section 7.3.6. Commit 7cd8407d53ef
("ACPI / PM: Do not execute _PS0 for devices without _PSC during
initialization") tried to workaround missing _PSC on defective
firmwares, but got reverted because of regression.

So the safest approach is to use acpi_device_fix_up_power_extended() to
put ACPI video and its child devices to D0 to workaround the issue.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217683
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v3:
 - Wording change to make it clear it's a firmware issue.
 - Specify the device name in comment.

v2:
 - Wording
 - Bugzilla
 - Add comment

 drivers/acpi/acpi_video.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Rafael J. Wysocki July 21, 2023, 3:45 p.m. UTC | #1 
Thanks for the update!

On Fri, Jul 21, 2023 at 5:22 PM Kai-Heng Feng
<kai.heng.feng@canonical.com> wrote:
>
> Screen brightness can only be changed once on HP ZBook Fury 16 G10.
>
> Vendor identified the root cause as Linux doesn't invoke _PS0 at boot
> for all ACPI devices:
>
>     Scope (\_SB.PC00.GFX0)
>     {
>         Scope (DD1F)
>         {
>             Method (_PS0, 0, Serialized)  // _PS0: Power State 0
>             {
>                 If (CondRefOf (\_SB.PC00.LPCB.EC0.SSBC))
>                 {
>                     \_SB.PC00.LPCB.EC0.SSBC ()
>                 }
>             }
>             ...
>         }
>         ...
>     }
>
> The \_SB.PC00.GFX0.DD1F is the panel device, and its _PS0 needs to be
> executed to make the brightness control work properly.
>
> _PS0 doesn't get invoked for this device because _PSC is missing,
> which violates ACPI spec 6.3, section 7.3.6. Commit 7cd8407d53ef
> ("ACPI / PM: Do not execute _PS0 for devices without _PSC during
> initialization") tried to workaround missing _PSC on defective
> firmwares, but got reverted because of regression.
>
> So the safest approach is to use acpi_device_fix_up_power_extended() to
> put ACPI video and its child devices to D0 to workaround the issue.
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217683
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>

Hans, what do you think?

> ---
> v3:
>  - Wording change to make it clear it's a firmware issue.
>  - Specify the device name in comment.
>
> v2:
>  - Wording
>  - Bugzilla
>  - Add comment
>
>  drivers/acpi/acpi_video.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
> index 62f4364e4460..1732780a672b 100644
> --- a/drivers/acpi/acpi_video.c
> +++ b/drivers/acpi/acpi_video.c
> @@ -2027,6 +2027,12 @@ static int acpi_video_bus_add(struct acpi_device *device)
>         if (error)
>                 goto err_put_video;
>
> +       /*
> +        * HP ZBook Fury 16 G10 requires ACPI video's child devices have _PS0
> +        * evaluated to have functional panel brightness control.
> +        */
> +       acpi_device_fix_up_power_extended(device);
> +
>         pr_info("%s [%s] (multi-head: %s  rom: %s  post: %s)\n",
>                ACPI_VIDEO_DEVICE_NAME, acpi_device_bid(device),
>                video->flags.multihead ? "yes" : "no",
> --
> 2.34.1
>
Hans de Goede July 25, 2023, 8:39 a.m. UTC | #2 
Hi,

On 7/21/23 17:45, Rafael J. Wysocki wrote:
> Thanks for the update!
> 
> On Fri, Jul 21, 2023 at 5:22 PM Kai-Heng Feng
> <kai.heng.feng@canonical.com> wrote:
>>
>> Screen brightness can only be changed once on HP ZBook Fury 16 G10.
>>
>> Vendor identified the root cause as Linux doesn't invoke _PS0 at boot
>> for all ACPI devices:
>>
>>     Scope (\_SB.PC00.GFX0)
>>     {
>>         Scope (DD1F)
>>         {
>>             Method (_PS0, 0, Serialized)  // _PS0: Power State 0
>>             {
>>                 If (CondRefOf (\_SB.PC00.LPCB.EC0.SSBC))
>>                 {
>>                     \_SB.PC00.LPCB.EC0.SSBC ()
>>                 }
>>             }
>>             ...
>>         }
>>         ...
>>     }
>>
>> The \_SB.PC00.GFX0.DD1F is the panel device, and its _PS0 needs to be
>> executed to make the brightness control work properly.
>>
>> _PS0 doesn't get invoked for this device because _PSC is missing,
>> which violates ACPI spec 6.3, section 7.3.6. Commit 7cd8407d53ef
>> ("ACPI / PM: Do not execute _PS0 for devices without _PSC during
>> initialization") tried to workaround missing _PSC on defective
>> firmwares, but got reverted because of regression.
>>
>> So the safest approach is to use acpi_device_fix_up_power_extended() to
>> put ACPI video and its child devices to D0 to workaround the issue.
>>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217683
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> 
> Hans, what do you think?

I believe most (almost all?) child devices of the GFX0 (and other
acpi-video) ACPI device will not have a _PS0. So wrt child-devices
this should mostly be a no-op.

However the GFX0 ACPI device is the ACPI companion for the PCI
device for the GPU, so this will also execute _PS0 on the GPU,
we do that every suspend/resume cycle so this should be fine.

But if we do see regressions then we may need to rework this
to skip the _PS0 on the GPU itself.

With that caveat this looks good to me:

Reviewed-by: Hans de Goede <hdegoede@redhat.com>

Regards,

Hans

> 
>> ---
>> v3:
>>  - Wording change to make it clear it's a firmware issue.
>>  - Specify the device name in comment.
>>
>> v2:
>>  - Wording
>>  - Bugzilla
>>  - Add comment
>>
>>  drivers/acpi/acpi_video.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
>> index 62f4364e4460..1732780a672b 100644
>> --- a/drivers/acpi/acpi_video.c
>> +++ b/drivers/acpi/acpi_video.c
>> @@ -2027,6 +2027,12 @@ static int acpi_video_bus_add(struct acpi_device *device)
>>         if (error)
>>                 goto err_put_video;
>>
>> +       /*
>> +        * HP ZBook Fury 16 G10 requires ACPI video's child devices have _PS0
>> +        * evaluated to have functional panel brightness control.
>> +        */
>> +       acpi_device_fix_up_power_extended(device);
>> +
>>         pr_info("%s [%s] (multi-head: %s  rom: %s  post: %s)\n",
>>                ACPI_VIDEO_DEVICE_NAME, acpi_device_bid(device),
>>                video->flags.multihead ? "yes" : "no",
>> --
>> 2.34.1
>>
>
Rafael J. Wysocki Aug. 17, 2023, 5:25 p.m. UTC | #3 
On Tue, Jul 25, 2023 at 10:39 AM Hans de Goede <hdegoede@redhat.com> wrote:
>
> Hi,
>
> On 7/21/23 17:45, Rafael J. Wysocki wrote:
> > Thanks for the update!
> >
> > On Fri, Jul 21, 2023 at 5:22 PM Kai-Heng Feng
> > <kai.heng.feng@canonical.com> wrote:
> >>
> >> Screen brightness can only be changed once on HP ZBook Fury 16 G10.
> >>
> >> Vendor identified the root cause as Linux doesn't invoke _PS0 at boot
> >> for all ACPI devices:
> >>
> >>     Scope (\_SB.PC00.GFX0)
> >>     {
> >>         Scope (DD1F)
> >>         {
> >>             Method (_PS0, 0, Serialized)  // _PS0: Power State 0
> >>             {
> >>                 If (CondRefOf (\_SB.PC00.LPCB.EC0.SSBC))
> >>                 {
> >>                     \_SB.PC00.LPCB.EC0.SSBC ()
> >>                 }
> >>             }
> >>             ...
> >>         }
> >>         ...
> >>     }
> >>
> >> The \_SB.PC00.GFX0.DD1F is the panel device, and its _PS0 needs to be
> >> executed to make the brightness control work properly.
> >>
> >> _PS0 doesn't get invoked for this device because _PSC is missing,
> >> which violates ACPI spec 6.3, section 7.3.6. Commit 7cd8407d53ef
> >> ("ACPI / PM: Do not execute _PS0 for devices without _PSC during
> >> initialization") tried to workaround missing _PSC on defective
> >> firmwares, but got reverted because of regression.
> >>
> >> So the safest approach is to use acpi_device_fix_up_power_extended() to
> >> put ACPI video and its child devices to D0 to workaround the issue.
> >>
> >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217683
> >> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> >
> > Hans, what do you think?
>
> I believe most (almost all?) child devices of the GFX0 (and other
> acpi-video) ACPI device will not have a _PS0. So wrt child-devices
> this should mostly be a no-op.
>
> However the GFX0 ACPI device is the ACPI companion for the PCI
> device for the GPU, so this will also execute _PS0 on the GPU,
> we do that every suspend/resume cycle so this should be fine.
>
> But if we do see regressions then we may need to rework this
> to skip the _PS0 on the GPU itself.
>
> With that caveat this looks good to me:
>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>

So I've edited the subject (slightly) and the changelog of this patch
and applied it as 6.6 material, thanks!
diff mbox series

Patch

diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
index 62f4364e4460..1732780a672b 100644
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -2027,6 +2027,12 @@  static int acpi_video_bus_add(struct acpi_device *device)
 	if (error)
 		goto err_put_video;
 
+	/*
+	 * HP ZBook Fury 16 G10 requires ACPI video's child devices have _PS0
+	 * evaluated to have functional panel brightness control.
+	 */
+	acpi_device_fix_up_power_extended(device);
+
 	pr_info("%s [%s] (multi-head: %s  rom: %s  post: %s)\n",
 	       ACPI_VIDEO_DEVICE_NAME, acpi_device_bid(device),
 	       video->flags.multihead ? "yes" : "no",