drm/xe/guc: Fix uninitialised count in GuC load debug prints

The debug prints about how long the GuC load takes have a loop
counter. However that was neither initialised nor incremented! Plus,
counting loops is no longer meaningful given the wait function returns
early for any change in the status value. So fix it to only count
loops due to actual timeouts.
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202405250151.IbH0l8FG-lkp@intel.com/
Fixes: b0ac1b42 ("drm/xe/guc: Port over the slow GuC loading support from i915")
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Oded Gabbay <ogabbay@kernel.org>
Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Fei Yang <fei.yang@intel.com>
Cc: intel-xe@lists.freedesktop.org
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240524202603.4011656-1-John.C.Harrison@Intel.com

drivers/gpu/drm/xe/xe_guc.c

@@ -591,7 +591,7 @@ static void guc_wait_ucode(struct xe_guc *guc)
 	ktime_t before, after, delta;
 	int load_done;
 	u32 status = 0;
-	int count;
+	int count = 0;
 	u64 delta_ms;
 	u32 before_freq;
 
@@ -604,6 +604,7 @@ static void guc_wait_ucode(struct xe_guc *guc)
 	 */
 	do {
 		u32 last_status = status & (GS_UKERNEL_MASK | GS_BOOTROM_MASK);
+		int ret;
 
 		/*
 		 * Wait for any change (intermediate or terminal) in the status register.
@@ -612,9 +613,10 @@ static void guc_wait_ucode(struct xe_guc *guc)
 		 * timeouts rather than allowing a huge timeout each time. So basically, need
 		 * to treat a timeout no different to a value change.
 		 */
-		xe_mmio_wait32_not(gt, GUC_STATUS, GS_UKERNEL_MASK | GS_BOOTROM_MASK,
-				   last_status, 1000 * 1000, &status, false);
-
+		ret = xe_mmio_wait32_not(gt, GUC_STATUS, GS_UKERNEL_MASK | GS_BOOTROM_MASK,
+					 last_status, 1000 * 1000, &status, false);
+		if (ret < 0)
+			count++;
 		after = ktime_get();
 		delta = ktime_sub(after, before);
 		delta_ms = ktime_to_ms(delta);
@@ -626,7 +628,7 @@ static void guc_wait_ucode(struct xe_guc *guc)
 		if (delta_ms >= (GUC_LOAD_RETRY_LIMIT * 1000))
 			break;
 
-		xe_gt_dbg(gt, "load still in progress, count = %d, freq = %dMHz (req %dMHz), status = 0x%08X [0x%02X/%02X]\n",
+		xe_gt_dbg(gt, "load still in progress, timeouts = %d, freq = %dMHz (req %dMHz), status = 0x%08X [0x%02X/%02X]\n",
 			  count, xe_guc_pc_get_act_freq(guc_pc),
 			  guc_pc_get_cur_freq(guc_pc), status,
 			  REG_FIELD_GET(GS_BOOTROM_MASK, status),
@@ -678,13 +680,13 @@ static void guc_wait_ucode(struct xe_guc *guc)
 
 		xe_device_declare_wedged(gt_to_xe(gt));
 	} else if (delta_ms > GUC_LOAD_TIME_WARN_MS) {
-		xe_gt_warn(gt, "excessive init time: %lldms! [status = 0x%08X, count = %d]\n",
+		xe_gt_warn(gt, "excessive init time: %lldms! [status = 0x%08X, timeouts = %d]\n",
 			   delta_ms, status, count);
 		xe_gt_warn(gt, "excessive init time: [freq = %dMHz (req = %dMHz), before = %dMHz, perf_limit_reasons = 0x%08X]\n",
 			   xe_guc_pc_get_act_freq(guc_pc), guc_pc_get_cur_freq(guc_pc),
 			   before_freq, xe_gt_throttle_get_limit_reasons(gt));
 	} else {
-		xe_gt_dbg(gt, "init took %lldms, freq = %dMHz (req = %dMHz), before = %dMHz, status = 0x%08X, count = %d\n",
+		xe_gt_dbg(gt, "init took %lldms, freq = %dMHz (req = %dMHz), before = %dMHz, status = 0x%08X, timeouts = %d\n",
 			  delta_ms, xe_guc_pc_get_act_freq(guc_pc), guc_pc_get_cur_freq(guc_pc),
 			  before_freq, status, count);
 	}