Commit b48ccb18 authored Mar 25, 2024 by Douglas Anderson

drm-panel: If drm_panel_dp_aux_backlight() fails, don't fail panel probe



If we're using the AUX channel for eDP backlight and it fails to probe
for some reason, let's _not_ fail the panel probe.

At least one case where we could fail to init the backlight is because
of a dead or physically missing panel. As talked about in detail in
the earlier patch in this series, ("drm/panel-edp: If we fail to
powerup/get EDID, use conservative timings"), this can cause the
entire system's display pipeline to fail to come up and that's
non-ideal.

If we fail to init the backlight for some transitory reason, we should
dig in and see if there's a way to fix this (perhaps retries?). Even
in that case, though, having a panel whose backlight is stuck at 100%
(the default, at least in the panel Samsung ATNA33XC20 I tested) is
better than having no panel at all.

Reviewed-by: Hsin-Yi Wang <hsinyi@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240325145626.3.I552e8af0ddb1691cc0fe5d27ea3d8020e36f7006@changeid

parent ce0ff223

drivers/gpu/drm/panel/panel-edp.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -944,8 +944,14 @@ static int panel_edp_probe(struct device dev, const struct panel_desc desc,
		err = drm_panel_dp_aux_backlight(&panel->base, panel->aux);
		pm_runtime_mark_last_busy(dev);
		pm_runtime_put_autosuspend(dev);

		/*
		* Warn if we get an error, but don't consider it fatal. Having
		* a panel where we can't control the backlight is better than
		* no panel.
		*/
		if (err)
		goto err_finished_pm_runtime;
		dev_warn(dev, "failed to register dp aux backlight: %d\n", err);
		}

		drm_panel_add(&panel->base);

drivers/gpu/drm/panel/panel-samsung-atna33xc20.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -328,9 +328,14 @@ static int atana33xc20_probe(struct dp_aux_ep_device *aux_ep)
		ret = drm_panel_dp_aux_backlight(&panel->base, aux_ep->aux);
		pm_runtime_mark_last_busy(dev);
		pm_runtime_put_autosuspend(dev);

		/*
		* Warn if we get an error, but don't consider it fatal. Having
		* a panel where we can't control the backlight is better than
		* no panel.
		*/
		if (ret)
		return dev_err_probe(dev, ret,
		"failed to register dp aux backlight\n");
		dev_warn(dev, "failed to register dp aux backlight: %d\n", ret);

		drm_panel_add(&panel->base);