imx-drm: ipu-dmfc: wait for FIFOs to run empty before disabling

Disabling the DMFC module while there is still data in the FIFOs could
cause the "new frame before end of frame" error state when the DMFC is
enabled again.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/drivers/staging/imx-drm/ipu-v3/ipu-dmfc.c b/drivers/staging/imx-drm/ipu-v3/ipu-dmfc.c
index 45213017fa4b3557e680843f05fad4adf4b19227..59f182b28fc1ce2e199aebf7d102407018c25fb6 100644 (file)
--- a/drivers/staging/imx-drm/ipu-v3/ipu-dmfc.c
+++ b/drivers/staging/imx-drm/ipu-v3/ipu-dmfc.c
@@ -28,7 +28,12 @@
 #define DMFC_GENERAL1          0x0014
 #define DMFC_GENERAL2          0x0018
 #define DMFC_IC_CTRL           0x001c
-#define DMFC_STAT              0x0020
+#define DMFC_WR_CHAN_ALT       0x0020
+#define DMFC_WR_CHAN_DEF_ALT   0x0024
+#define DMFC_DP_CHAN_ALT       0x0028
+#define DMFC_DP_CHAN_DEF_ALT   0x002c
+#define DMFC_GENERAL1_ALT      0x0030
+#define DMFC_STAT              0x0034
 
 #define DMFC_WR_CHAN_1_28              0
 #define DMFC_WR_CHAN_2_41              8
@@ -133,6 +138,20 @@ int ipu_dmfc_enable_channel(struct dmfc_channel *dmfc)
 }
 EXPORT_SYMBOL_GPL(ipu_dmfc_enable_channel);
 
+static void ipu_dmfc_wait_fifos(struct ipu_dmfc_priv *priv)
+{
+       unsigned long timeout = jiffies + msecs_to_jiffies(1000);
+
+       while ((readl(priv->base + DMFC_STAT) & 0x02fff000) != 0x02fff000) {
+               if (time_after(jiffies, timeout)) {
+                       dev_warn(priv->dev,
+                                "Timeout waiting for DMFC FIFOs to clear\n");
+                       break;
+               }
+               cpu_relax();
+       }
+}
+
 void ipu_dmfc_disable_channel(struct dmfc_channel *dmfc)
 {
        struct ipu_dmfc_priv *priv = dmfc->priv;
@@ -141,8 +160,10 @@ void ipu_dmfc_disable_channel(struct dmfc_channel *dmfc)
 
        priv->use_count--;
 
-       if (!priv->use_count)
+       if (!priv->use_count) {
+               ipu_dmfc_wait_fifos(priv);
                ipu_module_disable(priv->ipu, IPU_CONF_DMFC_EN);
+       }
 
        if (priv->use_count < 0)
                priv->use_count = 0;