[PATCH 8/9] drm/tegra: dpaux: Add missing runtime PM references

[Thierry Reding]

From: Thierry Reding <treding at nvidia.com>

Ensure that a runtime PM reference is acquired each time the DPAUX
registers are accessed. Otherwise the code may end up running without
the controller being powered, out-of-reset or clocked in some corner
cases, resulting in a crash.

Signed-off-by: Thierry Reding <treding at nvidia.com>
---
 drivers/gpu/drm/tegra/dpaux.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tegra/dpaux.c b/drivers/gpu/drm/tegra/dpaux.c
index 622cdf1ad246..4b2b86aed1a5 100644
--- a/drivers/gpu/drm/tegra/dpaux.c
+++ b/drivers/gpu/drm/tegra/dpaux.c
@@ -434,8 +434,13 @@ static int tegra_dpaux_set_mux(struct pinctrl_dev *pinctrl,
 			       unsigned int function, unsigned int group)
 {
 	struct tegra_dpaux *dpaux = pinctrl_dev_get_drvdata(pinctrl);
+	int err;
+
+	pm_runtime_get_sync(dpaux->dev);
+	err = tegra_dpaux_pad_config(dpaux, function);
+	pm_runtime_put(dpaux->dev);
 
-	return tegra_dpaux_pad_config(dpaux, function);
+	return err;
 }
 
 static const struct pinmux_ops tegra_dpaux_pinmux_ops = {
@@ -809,15 +814,22 @@ enum drm_connector_status drm_dp_aux_detect(struct drm_dp_aux *aux)
 int drm_dp_aux_enable(struct drm_dp_aux *aux)
 {
 	struct tegra_dpaux *dpaux = to_dpaux(aux);
+	int err;
+
+	pm_runtime_get_sync(dpaux->dev);
+	err = tegra_dpaux_pad_config(dpaux, DPAUX_PADCTL_FUNC_AUX);
+	pm_runtime_put(dpaux->dev);
 
-	return tegra_dpaux_pad_config(dpaux, DPAUX_PADCTL_FUNC_AUX);
+	return err;
 }
 
 int drm_dp_aux_disable(struct drm_dp_aux *aux)
 {
 	struct tegra_dpaux *dpaux = to_dpaux(aux);
 
+	pm_runtime_get_sync(dpaux->dev);
 	tegra_dpaux_pad_power_down(dpaux);
+	pm_runtime_put(dpaux->dev);
 
 	return 0;
 }
-- 
2.23.0