From 5ead9b5b157518520dd68b437f6d3640cefe608e Mon Sep 17 00:00:00 2001
From: Douglas Anderson <dianders@chromium.org>
Date: Wed, 14 Jul 2021 09:33:50 -0700
Subject: [PATCH] drm/panel-simple: Power the panel when probing DP AUX
 backlight

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>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210714093334.1.Idb41f87e5abae4aee0705db7458b0097fc50e7ab@changeid
---
 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 e0a05f366ce66..9b286bd4444fc 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;
 	}
-- 
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