drm/i915/dsi: wait for header and payload credit available

Driver should wait for free header or payload buffer in FIFO.
It would be good to wait a while for HW to release credit before
give it up to write to HW. Without sending initailize command
sets completely. It would caused MIPI display can't light up properly.

Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Vandita Kulkarni <vandita.kulkarni@intel.com>
Cc: Cooper Chiou <cooper.chiou@intel.com>
Cc: William Tseng <william.tseng@intel.com>
Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>
Reviewed-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210908115607.9633-2-shawn.c.lee@intel.com

drivers/gpu/drm/i915/display/icl_dsi.c

@@ -55,20 +55,28 @@ static int payload_credits_available(struct drm_i915_private *dev_priv,
 		>> FREE_PLOAD_CREDIT_SHIFT;
 }
 
-static void wait_for_header_credits(struct drm_i915_private *dev_priv,
-				    enum transcoder dsi_trans)
+static bool wait_for_header_credits(struct drm_i915_private *dev_priv,
+				    enum transcoder dsi_trans, int hdr_credit)
 {
 	if (wait_for_us(header_credits_available(dev_priv, dsi_trans) >=
-			MAX_HEADER_CREDIT, 100))
+			hdr_credit, 100)) {
 		drm_err(&dev_priv->drm, "DSI header credits not released\n");
+		return false;
+	}
+
+	return true;
 }
 
-static void wait_for_payload_credits(struct drm_i915_private *dev_priv,
-				     enum transcoder dsi_trans)
+static bool wait_for_payload_credits(struct drm_i915_private *dev_priv,
+				     enum transcoder dsi_trans, int payld_credit)
 {
 	if (wait_for_us(payload_credits_available(dev_priv, dsi_trans) >=
-			MAX_PLOAD_CREDIT, 100))
+			payld_credit, 100)) {
 		drm_err(&dev_priv->drm, "DSI payload credits not released\n");
+		return false;
+	}
+
+	return true;
 }
 
 static enum transcoder dsi_port_to_transcoder(enum port port)
@@ -91,8 +99,8 @@ static void wait_for_cmds_dispatched_to_panel(struct intel_encoder *encoder)
 	/* wait for header/payload credits to be released */
 	for_each_dsi_port(port, intel_dsi->ports) {
 		dsi_trans = dsi_port_to_transcoder(port);
-		wait_for_header_credits(dev_priv, dsi_trans);
-		wait_for_payload_credits(dev_priv, dsi_trans);
+		wait_for_header_credits(dev_priv, dsi_trans, MAX_HEADER_CREDIT);
+		wait_for_payload_credits(dev_priv, dsi_trans, MAX_PLOAD_CREDIT);
 	}
 
 	/* send nop DCS command */
@@ -109,7 +117,7 @@ static void wait_for_cmds_dispatched_to_panel(struct intel_encoder *encoder)
 	/* wait for header credits to be released */
 	for_each_dsi_port(port, intel_dsi->ports) {
 		dsi_trans = dsi_port_to_transcoder(port);
-		wait_for_header_credits(dev_priv, dsi_trans);
+		wait_for_header_credits(dev_priv, dsi_trans, MAX_HEADER_CREDIT);
 	}
 
 	/* wait for LP TX in progress bit to be cleared */
@@ -127,18 +135,13 @@ static bool add_payld_to_queue(struct intel_dsi_host *host, const u8 *data,
 	struct intel_dsi *intel_dsi = host->intel_dsi;
 	struct drm_i915_private *dev_priv = to_i915(intel_dsi->base.base.dev);
 	enum transcoder dsi_trans = dsi_port_to_transcoder(host->port);
-	int free_credits;
 	int i, j;
 
 	for (i = 0; i < len; i += 4) {
 		u32 tmp = 0;
 
-		free_credits = payload_credits_available(dev_priv, dsi_trans);
-		if (free_credits < 1) {
-			drm_err(&dev_priv->drm,
-				"Payload credit not available\n");
+		if (!wait_for_payload_credits(dev_priv, dsi_trans, 1))
 			return false;
-		}
 
 		for (j = 0; j < min_t(u32, len - i, 4); j++)
 			tmp |= *data++ << 8 * j;
@@ -156,15 +159,10 @@ static int dsi_send_pkt_hdr(struct intel_dsi_host *host,
 	struct drm_i915_private *dev_priv = to_i915(intel_dsi->base.base.dev);
 	enum transcoder dsi_trans = dsi_port_to_transcoder(host->port);
 	u32 tmp;
-	int free_credits;
 
 	/* check if header credit available */
-	free_credits = header_credits_available(dev_priv, dsi_trans);
-	if (free_credits < 1) {
-		drm_err(&dev_priv->drm,
-			"send pkt header failed, not enough hdr credits\n");
+	if (!wait_for_header_credits(dev_priv, dsi_trans, 1))
 		return -1;
-	}
 
 	tmp = intel_de_read(dev_priv, DSI_CMD_TXHDR(dsi_trans));