[PATCH 14/72] gpu: ipu-v3: Implement use counter for ipu_dc_enable(), ipu_dc_disable()

[Steve Longerbeam]

The functions ipu_dc_enable() and ipu_dc_disable() enable/disable the DC
globally in the IPU_CONF register, but the DC is used by multiple clients
on different DC channels. So make sure to only disable/enable the DC
globally based on a use counter.

Signed-off-by: Steve Longerbeam <steve_longerbeam at mentor.com>
---
 drivers/gpu/ipu-v3/ipu-dc.c |   21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/ipu-v3/ipu-dc.c b/drivers/gpu/ipu-v3/ipu-dc.c
index f53fce5..79879e7 100644
--- a/drivers/gpu/ipu-v3/ipu-dc.c
+++ b/drivers/gpu/ipu-v3/ipu-dc.c
@@ -144,6 +144,7 @@ struct ipu_dc_priv {
 	struct completion	comp;
 	int			dc_irq;
 	int			dp_irq;
+	int			use_count;
 };
 
 /* forward references */
@@ -345,7 +346,14 @@ void ipu_dc_enable(struct ipu_dc *dc)
 {
 	struct ipu_dc_priv *priv = dc->priv;
 
-	ipu_module_enable(priv->ipu, IPU_CONF_DC_EN);
+	mutex_lock(&priv->mutex);
+
+	if (!priv->use_count)
+		ipu_module_enable(priv->ipu, IPU_CONF_DC_EN);
+
+	priv->use_count++;
+
+	mutex_unlock(&priv->mutex);
 }
 EXPORT_SYMBOL_GPL(ipu_dc_enable);
 
@@ -409,7 +417,16 @@ void ipu_dc_disable(struct ipu_dc *dc)
 {
 	struct ipu_dc_priv *priv = dc->priv;
 
-	ipu_module_disable(priv->ipu, IPU_CONF_DC_EN);
+	mutex_lock(&priv->mutex);
+
+	priv->use_count--;
+	if (!priv->use_count)
+		ipu_module_disable(priv->ipu, IPU_CONF_DC_EN);
+
+	if (priv->use_count < 0)
+		priv->use_count = 0;
+
+	mutex_unlock(&priv->mutex);
 }
 EXPORT_SYMBOL_GPL(ipu_dc_disable);
 
-- 
1.7.9.5