[PATCH] drm/i915/gsc: Improve SW proxy error checking and logging

[Daniele Ceraolo Spurio]

If an error occurs in the GSC<->CSME handshake, the GSC will send a
PROXY_END msg to the driver with the status set to an error code. We
currently don't check the status when receiving a PROXY_END message and
instead check the proxy initialization status in the FWSTS reg;
therefore, while still catching any initialization failures, we lose the
actual returned error code. This can be easily improved by checking the
status value and printing it to dmesg if it's an error.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Cc: Alan Previn <alan.previn.teres.alexis at intel.com>
---
 drivers/gpu/drm/i915/gt/uc/intel_gsc_proxy.c | 26 ++++++++++++++++----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_gsc_proxy.c b/drivers/gpu/drm/i915/gt/uc/intel_gsc_proxy.c
index d8edd7c054c8..cf114361cf59 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_gsc_proxy.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_gsc_proxy.c
@@ -155,7 +155,8 @@ static int proxy_send_to_gsc(struct intel_gsc_uc *gsc)
 	return err;
 }
 
-static int validate_proxy_header(struct intel_gsc_proxy_header *header,
+static int validate_proxy_header(struct intel_gt *gt,
+				 struct intel_gsc_proxy_header *header,
 				 u32 source, u32 dest)
 {
 	u32 type = FIELD_GET(GSC_PROXY_TYPE, header->hdr);
@@ -167,6 +168,12 @@ static int validate_proxy_header(struct intel_gsc_proxy_header *header,
 		goto fail;
 	}
 
+	/* We only care about the status if this is a message for the driver */
+	if (dest == GSC_PROXY_ADDRESSING_KMD && header->status != 0) {
+		ret = -EIO;
+		goto fail;
+	}
+
 	switch (type) {
 	case GSC_PROXY_MSG_TYPE_PROXY_PAYLOAD:
 		if (length > 0)
@@ -180,6 +187,11 @@ static int validate_proxy_header(struct intel_gsc_proxy_header *header,
 	}
 
 fail:
+	if (ret)
+		gt_err(gt,
+		       "GSC proxy error: s=0x%x[0x%x], d=0x%x[0x%x], t=%u, l=0x%x, st=0x%x\n",
+		       header->source, source, header->destination, dest,
+		       type, length, header->status);
 	return ret;
 }
 
@@ -214,13 +226,17 @@ static int proxy_query(struct intel_gsc_uc *gsc)
 			goto proxy_error;
 		}
 
-		/* stop if this was the last message */
+		/* Check the status and stop if this was the last message */
 		if (FIELD_GET(GSC_PROXY_TYPE, to_csme->proxy_header.hdr) ==
-				GSC_PROXY_MSG_TYPE_PROXY_END)
+				GSC_PROXY_MSG_TYPE_PROXY_END) {
+			ret = validate_proxy_header(gt, &to_csme->proxy_header,
+						    GSC_PROXY_ADDRESSING_GSC,
+						    GSC_PROXY_ADDRESSING_KMD);
 			break;
+		}
 
 		/* make sure the GSC-to-CSME proxy header is sane */
-		ret = validate_proxy_header(&to_csme->proxy_header,
+		ret = validate_proxy_header(gt, &to_csme->proxy_header,
 					    GSC_PROXY_ADDRESSING_GSC,
 					    GSC_PROXY_ADDRESSING_CSME);
 		if (ret) {
@@ -239,7 +255,7 @@ static int proxy_query(struct intel_gsc_uc *gsc)
 		to_gsc->header.message_size = ret + sizeof(struct intel_gsc_mtl_header);
 
 		/* make sure the CSME-to-GSC proxy header is sane */
-		ret = validate_proxy_header(&to_gsc->proxy_header,
+		ret = validate_proxy_header(gt, &to_gsc->proxy_header,
 					    GSC_PROXY_ADDRESSING_CSME,
 					    GSC_PROXY_ADDRESSING_GSC);
 		if (ret) {
-- 
2.43.0