[PATCH] drm/panel-simple: Power the panel when probing DP AUX backlight

[PATCH] drm/panel-simple: Power the panel when probing DP AUX backlight

[Douglas Anderson]

When I tried booting up a device that needed the DP AUX backlight, I
found an error in the logs:
  panel-simple-dp-aux: probe of aux-ti_sn65dsi86.aux.0 failed with error -110

The aux transfers were failing because the panel wasn't powered. Just
like when reading the EDID we need to power the panel when trying to
talk to it. Add the needed pm_runtime calls.

After I do this I can successfully probe the panel and adjust the
backlight on my board.

Fixes: bfd451403d70 ("drm/panel-simple: Support DP AUX backlight")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

 drivers/gpu/drm/panel/panel-simple.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index e0a05f366ce6..9b286bd4444f 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -827,7 +827,10 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc,
 		goto disable_pm_runtime;
 
 	if (!panel->base.backlight && panel->aux) {
+		pm_runtime_get_sync(dev);
 		err = drm_panel_dp_aux_backlight(&panel->base, panel->aux);
+		pm_runtime_mark_last_busy(dev);
+		pm_runtime_put_autosuspend(dev);
 		if (err)
 			goto disable_pm_runtime;
 	}
-- 
2.32.0.93.g670b81a890-goog

Re: [PATCH] drm/panel-simple: Power the panel when probing DP AUX backlight

[Lyude Paul]

Reviewed-by: Lyude Paul <lyude@redhat.com>

On Wed, 2021-07-14 at 09:33 -0700, Douglas Anderson wrote:
> When I tried booting up a device that needed the DP AUX backlight, I
> found an error in the logs:
>   panel-simple-dp-aux: probe of aux-ti_sn65dsi86.aux.0 failed with error -
> 110
> 
> The aux transfers were failing because the panel wasn't powered. Just
> like when reading the EDID we need to power the panel when trying to
> talk to it. Add the needed pm_runtime calls.
> 
> After I do this I can successfully probe the panel and adjust the
> backlight on my board.
> 
> Fixes: bfd451403d70 ("drm/panel-simple: Support DP AUX backlight")
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> 
>  drivers/gpu/drm/panel/panel-simple.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-simple.c
> b/drivers/gpu/drm/panel/panel-simple.c
> index e0a05f366ce6..9b286bd4444f 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -827,7 +827,10 @@ static int panel_simple_probe(struct device *dev, const
> struct panel_desc *desc,
>                 goto disable_pm_runtime;
>  
>         if (!panel->base.backlight && panel->aux) {
> +               pm_runtime_get_sync(dev);
>                 err = drm_panel_dp_aux_backlight(&panel->base, panel->aux);
> +               pm_runtime_mark_last_busy(dev);
> +               pm_runtime_put_autosuspend(dev);
>                 if (err)
>                         goto disable_pm_runtime;
>         }

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat

Re: [PATCH] drm/panel-simple: Power the panel when probing DP AUX backlight

[Doug Anderson]

Hi,

On Wed, Jul 14, 2021 at 9:34 AM Douglas Anderson <dianders@chromium.org> wrote:
>
> When I tried booting up a device that needed the DP AUX backlight, I
> found an error in the logs:
>   panel-simple-dp-aux: probe of aux-ti_sn65dsi86.aux.0 failed with error -110
>
> The aux transfers were failing because the panel wasn't powered. Just
> like when reading the EDID we need to power the panel when trying to
> talk to it. Add the needed pm_runtime calls.
>
> After I do this I can successfully probe the panel and adjust the
> backlight on my board.
>
> Fixes: bfd451403d70 ("drm/panel-simple: Support DP AUX backlight")
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
>
>  drivers/gpu/drm/panel/panel-simple.c | 3 +++
>  1 file changed, 3 insertions(+)

Pushed with Lyude's review to drm-misc-next:

5ead9b5b1575 drm/panel-simple: Power the panel when probing DP AUX backlight