The bridge might miss the display change events when it's powered off.
This happens when a user changes the external monitor when the system
is suspended and the embedded controller doesn't not wake AP up.

It's also observed that one DP-to-HDMI bridge doesn't work correctly
when there is no EDID read after it is powered on.

Drop the cache to force an EDID read after system resume to fix this.

Fixes: 11feaef69d0c ("drm/bridge: it6505: Add caching for EDID")
Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>

---

Changes in v2:
- Collect review tags

 drivers/gpu/drm/bridge/ite-it6505.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index 1e1c06fdf206..bb449efac2f4 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -3101,6 +3101,8 @@ static __maybe_unused int it6505_bridge_suspend(struct device *dev)
 {
 	struct it6505 *it6505 = dev_get_drvdata(dev);
 
+	it6505_remove_edid(it6505);
+
 	return it6505_poweroff(it6505);
 }
 
-- 
2.46.0.792.g87dc391469-goog

Hi,

On Thu, Sep 26, 2024 at 2:29 AM Pin-yen Lin <treapking@chromium.org> wrote:
>
> The bridge might miss the display change events when it's powered off.
> This happens when a user changes the external monitor when the system
> is suspended and the embedded controller doesn't not wake AP up.
>
> It's also observed that one DP-to-HDMI bridge doesn't work correctly
> when there is no EDID read after it is powered on.
>
> Drop the cache to force an EDID read after system resume to fix this.
>
> Fixes: 11feaef69d0c ("drm/bridge: it6505: Add caching for EDID")
> Signed-off-by: Pin-yen Lin <treapking@chromium.org>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Reviewed-by: Douglas Anderson <dianders@chromium.org>
>
> ---
>
> Changes in v2:
> - Collect review tags
>
>  drivers/gpu/drm/bridge/ite-it6505.c | 2 ++
>  1 file changed, 2 insertions(+)

Like with patch #1, meant to push to drm-misc-fixes but ended up on
drm-misc-next. Yell if this is a problem, but I think it should be OK.

[2/2] drm/bridge: it6505: Drop EDID cache on bridge power off
      commit: 574c558ddb68591c9a4b7a95e45e935ab22c0fc6

-Doug