[PATCH 1/3] drm/tilcdc: Take mode config lock while updating the crtc clock rate

[Jyri Sarha]

Take mode config lock while updating the crtc clock rate. To avoid a
race in tilcdc_crtc_update_clk(), we do not want the mode to change
while we update crtc clock.

Signed-off-by: Jyri Sarha <jsarha at ti.com>
---
 drivers/gpu/drm/tilcdc/tilcdc_drv.c | 5 +++++
 drivers/gpu/drm/tilcdc/tilcdc_drv.h | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.c b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
index f8892e9..882d9b5 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
@@ -184,10 +184,14 @@ static int cpufreq_transition(struct notifier_block *nb,
 {
 	struct tilcdc_drm_private *priv = container_of(nb,
 			struct tilcdc_drm_private, freq_transition);
+	struct drm_mode_config *config = &priv->dev->mode_config;
+
 	if (val == CPUFREQ_POSTCHANGE) {
 		if (priv->lcd_fck_rate != clk_get_rate(priv->clk)) {
+			mutex_lock(&config->mutex);
 			priv->lcd_fck_rate = clk_get_rate(priv->clk);
 			tilcdc_crtc_update_clk(priv->crtc);
+			mutex_unlock(&config->mutex);
 		}
 	}
 
@@ -251,6 +255,7 @@ static int tilcdc_load(struct drm_device *dev, unsigned long flags)
 	}
 
 	dev->dev_private = priv;
+	priv->dev = dev;
 
 	priv->is_componentized =
 		tilcdc_get_external_components(dev->dev, NULL) > 0;
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.h b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
index a6e5e6d..6caecfc 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.h
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
@@ -49,6 +49,8 @@
 struct tilcdc_drm_private {
 	void __iomem *mmio;
 
+	struct drm_device *dev;
+
 	struct clk *clk;         /* functional clock */
 	int rev;                 /* IP revision */
 
-- 
1.9.1