[Intel-gfx] [PATCH] drm/i915/ehl: Resolve insufficient header credits in MIPI DSI

[Aria Kraft]

MIPI DSI initialization on EHL can fail due to not enough header credits available.

To resolve this failure, this patch adds a header count to the existing 100us wait function.

It then adds a call to this modified function to request a single header credit during initialization.

Reviewed-by: Bob Paauwe <bob.j.paauwe at intel.com>
Signed-off-by: Aria Kraft <aria.m.kraft at intel.com>
---
 drivers/gpu/drm/i915/display/icl_dsi.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
index 43ec7fcd3f5d..fd836fdc6ec7 100644
--- a/drivers/gpu/drm/i915/display/icl_dsi.c
+++ b/drivers/gpu/drm/i915/display/icl_dsi.c
@@ -54,12 +54,15 @@ 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, unsigned int credits)
 {
 	if (wait_for_us(header_credits_available(dev_priv, dsi_trans) >=
-			MAX_HEADER_CREDIT, 100))
+			credits, 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,
@@ -90,7 +93,7 @@ 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_header_credits(dev_priv, dsi_trans, MAX_HEADER_CREDIT);
 		wait_for_payload_credits(dev_priv, dsi_trans);
 	}
 
@@ -108,7 +111,7 @@ 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 */
@@ -155,13 +158,9 @@ 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;
 	}
 
-- 
2.31.1