gpu: ipu-v3: dp: fix CSC handling

Initialize the flow input colorspaces to unknown and reset to that value
when the channel gets disabled. This avoids the state getting mixed up
with a previous mode.

Also keep the CSC settings for the background flow intact when disabling
the foreground flow.
Root-caused-by: NJonathan Marek <jonathan@marek.ca>
Signed-off-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/ipu-v3/ipu-dp.c

@@ -195,7 +195,8 @@ int ipu_dp_setup_channel(struct ipu_dp *dp,
 		ipu_dp_csc_init(flow, flow->foreground.in_cs, flow->out_cs,
 				DP_COM_CONF_CSC_DEF_BOTH);
 	} else {
-		if (flow->foreground.in_cs == flow->out_cs)
+		if (flow->foreground.in_cs == IPUV3_COLORSPACE_UNKNOWN ||
+		    flow->foreground.in_cs == flow->out_cs)
 			/*
 			 * foreground identical to output, apply color
 			 * conversion on background
@@ -261,6 +262,8 @@ void ipu_dp_disable_channel(struct ipu_dp *dp, bool sync)
 	struct ipu_dp_priv *priv = flow->priv;
 	u32 reg, csc;
 
+	dp->in_cs = IPUV3_COLORSPACE_UNKNOWN;
+
 	if (!dp->foreground)
 		return;
 
@@ -268,8 +271,9 @@ void ipu_dp_disable_channel(struct ipu_dp *dp, bool sync)
 
 	reg = readl(flow->base + DP_COM_CONF);
 	csc = reg & DP_COM_CONF_CSC_DEF_MASK;
-	if (csc == DP_COM_CONF_CSC_DEF_FG)
-		reg &= ~DP_COM_CONF_CSC_DEF_MASK;
+	reg &= ~DP_COM_CONF_CSC_DEF_MASK;
+	if (csc == DP_COM_CONF_CSC_DEF_BOTH || csc == DP_COM_CONF_CSC_DEF_BG)
+		reg |= DP_COM_CONF_CSC_DEF_BG;
 
 	reg &= ~DP_COM_CONF_FG_EN;
 	writel(reg, flow->base + DP_COM_CONF);
@@ -347,6 +351,8 @@ int ipu_dp_init(struct ipu_soc *ipu, struct device *dev, unsigned long base)
 	mutex_init(&priv->mutex);
 
 	for (i = 0; i < IPUV3_NUM_FLOWS; i++) {
+		priv->flow[i].background.in_cs = IPUV3_COLORSPACE_UNKNOWN;
+		priv->flow[i].foreground.in_cs = IPUV3_COLORSPACE_UNKNOWN;
 		priv->flow[i].foreground.foreground = true;
 		priv->flow[i].base = priv->base + ipu_dp_flow_base[i];
 		priv->flow[i].priv = priv;