[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