drm/i915/guc: Trace messages from CT while in debug

During debug we may want to investigate all communication
from the Guc. Add proper tracing macros in debug config.

v2: convert remaining DRM_DEBUG into new CT_DEBUG (Michal)
v3: use dedicated Kconfig (Daniele)
v4: checkpatch
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180326194829.58836-12-michal.wajdeczko@intel.com

drivers/gpu/drm/i915/Kconfig.debug

@@ -90,6 +90,18 @@ config DRM_I915_SW_FENCE_CHECK_DAG
 
           If in doubt, say "N".
 
+config DRM_I915_DEBUG_GUC
+        bool "Enable additional driver debugging for GuC"
+        depends on DRM_I915
+        default n
+        help
+          Choose this option to turn on extra driver debugging that may affect
+          performance but will help resolve GuC related issues.
+
+          Recommended for driver developers only.
+
+          If in doubt, say "N".
+
 config DRM_I915_SELFTEST
 	bool "Enable selftests upon driver load"
 	depends on DRM_I915

drivers/gpu/drm/i915/intel_guc_ct.c

@@ -24,6 +24,12 @@
 #include "i915_drv.h"
 #include "intel_guc_ct.h"
 
+#ifdef CONFIG_DRM_I915_DEBUG_GUC
+#define CT_DEBUG_DRIVER(...)	DRM_DEBUG_DRIVER(__VA_ARGS__)
+#else
+#define CT_DEBUG_DRIVER(...)	do { } while (0)
+#endif
+
 struct ct_request {
 	struct list_head link;
 	u32 fence;
@@ -78,7 +84,7 @@ static inline const char *guc_ct_buffer_type_to_str(u32 type)
 static void guc_ct_buffer_desc_init(struct guc_ct_buffer_desc *desc,
 				    u32 cmds_addr, u32 size, u32 owner)
 {
-	DRM_DEBUG_DRIVER("CT: desc %p init addr=%#x size=%u owner=%u\n",
+	CT_DEBUG_DRIVER("CT: desc %p init addr=%#x size=%u owner=%u\n",
 			desc, cmds_addr, size, owner);
 	memset(desc, 0, sizeof(*desc));
 	desc->addr = cmds_addr;
@@ -88,7 +94,7 @@ static void guc_ct_buffer_desc_init(struct guc_ct_buffer_desc *desc,
 
 static void guc_ct_buffer_desc_reset(struct guc_ct_buffer_desc *desc)
 {
-	DRM_DEBUG_DRIVER("CT: desc %p reset head=%u tail=%u\n",
+	CT_DEBUG_DRIVER("CT: desc %p reset head=%u tail=%u\n",
 			desc, desc->head, desc->tail);
 	desc->head = 0;
 	desc->tail = 0;
@@ -185,7 +191,7 @@ static int ctch_init(struct intel_guc *guc,
 		err = PTR_ERR(blob);
 		goto err_vma;
 	}
-	DRM_DEBUG_DRIVER("CT: vma base=%#x\n",
+	CT_DEBUG_DRIVER("CT: vma base=%#x\n",
 			intel_guc_ggtt_offset(guc, ctch->vma));
 
 	/* store pointers to desc and cmds */
@@ -200,7 +206,7 @@ static int ctch_init(struct intel_guc *guc,
 err_vma:
 	i915_vma_unpin_and_release(&ctch->vma);
 err_out:
-	DRM_DEBUG_DRIVER("CT: channel %d initialization failed; err=%d\n",
+	CT_DEBUG_DRIVER("CT: channel %d initialization failed; err=%d\n",
 			ctch->owner, err);
 	return err;
 }
@@ -221,7 +227,7 @@ static int ctch_open(struct intel_guc *guc,
 	int err;
 	int i;
 
-	DRM_DEBUG_DRIVER("CT: channel %d reopen=%s\n",
+	CT_DEBUG_DRIVER("CT: channel %d reopen=%s\n",
 			ctch->owner, yesno(ctch_is_open(ctch)));
 
 	if (!ctch->vma) {
@@ -355,6 +361,10 @@ static int ctb_write(struct intel_guc_ct_buffer *ctb,
 		 (want_response ? GUC_CT_MSG_SEND_STATUS : 0) |
 		 (action[0] << GUC_CT_MSG_ACTION_SHIFT);
 
+	CT_DEBUG_DRIVER("CT: writing %*phn %*phn %*phn\n",
+			4, &header, 4, &fence,
+			4 * (len - 1), &action[1]);
+
 	cmds[tail] = header;
 	tail = (tail + 1) % size;
 
@@ -545,6 +555,9 @@ static int intel_guc_send_ct(struct intel_guc *guc, const u32 *action, u32 len,
 	if (unlikely(ret < 0)) {
 		DRM_ERROR("CT: send action %#X failed; err=%d status=%#X\n",
 			  action[0], ret, status);
+	} else if (unlikely(ret)) {
+		CT_DEBUG_DRIVER("CT: send action %#x returned %d (%#x)\n",
+				action[0], ret, ret);
 	}
 
 	mutex_unlock(&guc->send_mutex);
@@ -591,6 +604,7 @@ static int ctb_read(struct intel_guc_ct_buffer *ctb, u32 *data)
 	/* beware of buffer wrap case */
 	if (unlikely(available < 0))
 		available += size;
+	CT_DEBUG_DRIVER("CT: available %d (%u:%u)\n", available, head, tail);
 	GEM_BUG_ON(available < 0);
 
 	data[0] = cmds[head];
@@ -612,6 +626,7 @@ static int ctb_read(struct intel_guc_ct_buffer *ctb, u32 *data)
 		data[i] = cmds[head];
 		head = (head + 1) % size;
 	}
+	CT_DEBUG_DRIVER("CT: received %*phn\n", 4 * len, data);
 
 	desc->head = head * 4;
 	return 0;
@@ -665,10 +680,12 @@ static int ct_handle_response(struct intel_guc_ct *ct, const u32 *msg)
 		return -EPROTO;
 	}
 
+	CT_DEBUG_DRIVER("CT: response fence %u status %#x\n", fence, status);
+
 	spin_lock(&ct->lock);
 	list_for_each_entry(req, &ct->pending_requests, link) {
 		if (unlikely(fence != req->fence)) {
-			DRM_DEBUG_DRIVER("CT: request %u awaits response\n",
+			CT_DEBUG_DRIVER("CT: request %u awaits response\n",
 					req->fence);
 			continue;
 		}
@@ -696,6 +713,8 @@ static void ct_process_request(struct intel_guc_ct *ct,
 {
 	struct intel_guc *guc = ct_to_guc(ct);
 
+	CT_DEBUG_DRIVER("CT: request %x %*phn\n", action, 4 * len, payload);
+
 	switch (action) {
 	case INTEL_GUC_ACTION_DEFAULT:
 		if (unlikely(len < 1))