[SRU v2] [F/G/Unstable/OEM-5.10] [PATCH 0/1] Use DCPD to control HP DreamColor panel

[Kai-Heng Feng]

BugLink: https://bugs.launchpad.net/bugs/1911001

[Impact]
Cannot change brightness on HP ZBook Fury with certain panel.

[Fix]
Add the panel to DPCD quirk table to use DPCD to control the panel
backlight.

[Test]
Changing backlight sysfs doesn't change the display brightness.
With the patch applied, changing sysfs backlight can really change the
display brightness.

[Where problems could occur]
This fix is specific to a single panel, so it's not likely to cause any
regression to other devices.

Kai-Heng Feng (1):
  UBUNTU: SAUCE: drm/dp: Another HP DreamColor panel brigntness fix

 drivers/gpu/drm/drm_dp_helper.c | 1 +
 1 file changed, 1 insertion(+)

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[Kai-Heng Feng]

BugLink: https://bugs.launchpad.net/bugs/1911001

Another HP DreamColor panel, which is used by new HP ZBook Fury, needs
to use DPCD to control brightness.

Once the proper fix [1] is merged, this can be dropped.

[1] https://patchwork.freedesktop.org/series/81702/

Signed-off-by: Kai-Heng Feng <[hidden email]>
---
 drivers/gpu/drm/drm_dp_helper.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index c55c14453ecb..efd50e87ec99 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -1881,6 +1881,7 @@ static const struct edid_quirk edid_quirk_list[] = {
  * controls anyway...). Until we have a better way of detecting these,
  * force DPCD backlight mode on all of them.
  */
+ { MFG(0x06, 0xaf), PROD_ID(0x8c, 0xcd), BIT(DP_QUIRK_FORCE_DPCD_BACKLIGHT) },
  { MFG(0x06, 0xaf), PROD_ID(0x9b, 0x32), BIT(DP_QUIRK_FORCE_DPCD_BACKLIGHT) },
  { MFG(0x06, 0xaf), PROD_ID(0xeb, 0x41), BIT(DP_QUIRK_FORCE_DPCD_BACKLIGHT) },
  { MFG(0x30, 0xe4), PROD_ID(0x61, 0x06), BIT(DP_QUIRK_FORCE_DPCD_BACKLIGHT) },
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[Timo Aaltonen-6]

On 12.1.2021 12.54, Kai-Heng Feng wrote:

> BugLink: https://bugs.launchpad.net/bugs/1911001
>
> [Impact]
> Cannot change brightness on HP ZBook Fury with certain panel.
>
> [Fix]
> Add the panel to DPCD quirk table to use DPCD to control the panel
> backlight.
>
> [Test]
> Changing backlight sysfs doesn't change the display brightness.
> With the patch applied, changing sysfs backlight can really change the
> display brightness.
>
> [Where problems could occur]
> This fix is specific to a single panel, so it's not likely to cause any
> regression to other devices.
>
> Kai-Heng Feng (1):
>    UBUNTU: SAUCE: drm/dp: Another HP DreamColor panel brigntness fix
>
>   drivers/gpu/drm/drm_dp_helper.c | 1 +
>   1 file changed, 1 insertion(+)
>

applied to oem-5.10, thanks

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