[PATCH v2 1/2] drm/panel-edp: fix i2c adapter leak on probe failure

[Johan Hovold <johan@kernel.org>]

Make sure to drop the i2c adapter reference on probe failure (e.g.
probe deferral) and on driver unbind also if a devicetree redundantly
uses the 'ddc-i2c-bus' property to point to the aux ddc bus.

Fixes: cc5a3fc041f0 ("drm/panel: panel-simple: Stash DP AUX bus; allow using it for DDC")
Cc: stable@vger.kernel.org	# 5.15
Reported-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/CAD=FV=VZPhzHU+Pet2m3L+Pqc7mOPfZC-f5p0OuNL79wNZPxRg@mail.gmail.com
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/gpu/drm/panel/panel-edp.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
index aa27d6cd932e..ac815729aa83 100644
--- a/drivers/gpu/drm/panel/panel-edp.c
+++ b/drivers/gpu/drm/panel/panel-edp.c
@@ -831,6 +831,13 @@ static int generic_edp_panel_probe(struct device *dev, struct panel_edp *panel)
 	return 0;
 }
 
+static void panel_edp_put_adapter(void *_adap)
+{
+	struct i2c_adapter *adap = _adap;
+
+	put_device(&adap->dev);
+}
+
 static int panel_edp_probe(struct device *dev, const struct panel_desc *desc,
 			   struct drm_dp_aux *aux)
 {
@@ -878,6 +885,11 @@ static int panel_edp_probe(struct device *dev, const struct panel_desc *desc,
 
 		if (!panel->ddc)
 			return -EPROBE_DEFER;
+
+		err = devm_add_action_or_reset(dev, panel_edp_put_adapter,
+					       panel->ddc);
+		if (err)
+			return err;
 	} else if (aux) {
 		panel->ddc = &aux->ddc;
 	}
@@ -889,7 +901,7 @@ static int panel_edp_probe(struct device *dev, const struct panel_desc *desc,
 
 	err = drm_panel_of_backlight(&panel->base);
 	if (err)
-		goto err_finished_ddc_init;
+		return err;
 
 	/*
 	 * We use runtime PM for prepare / unprepare since those power the panel
@@ -936,9 +948,6 @@ static int panel_edp_probe(struct device *dev, const struct panel_desc *desc,
 err_finished_pm_runtime:
 	pm_runtime_dont_use_autosuspend(dev);
 	pm_runtime_disable(dev);
-err_finished_ddc_init:
-	if (panel->ddc && (!panel->aux || panel->ddc != &panel->aux->ddc))
-		put_device(&panel->ddc->dev);
 
 	return err;
 }
@@ -982,8 +991,6 @@ static void panel_edp_remove(struct device *dev)
 
 	pm_runtime_dont_use_autosuspend(dev);
 	pm_runtime_disable(dev);
-	if (panel->ddc && (!panel->aux || panel->ddc != &panel->aux->ddc))
-		put_device(&panel->ddc->dev);
 
 	drm_edid_free(panel->drm_edid);
 	panel->drm_edid = NULL;
-- 
2.54.0