drm/xe/xe_guc_pc: Lock once to update stashed frequencies

pc_set_mert_freq_cap() currently lock()/unlock() the mutex multiple times
to stash the current frequencies. It's not a problem since
xe_guc_pc_restore_stashed_freq() is guaranteed to be called only later
in the init sequence. However, now that we have _locked() variants for
this functions, use them and avoid potential issues when called from
other places or using the same pattern.

While at it, prefer and early return for the WA check to reduce
indentation.

Reviewed-by: Rodrigo Vivi <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Lucas De Marchi <[email protected]>
(cherry picked from commit d878c97)
Signed-off-by: Lucas De Marchi <[email protected]>

Author: Lucas De Marchi

drivers/gpu/drm/xe/xe_guc_pc.c

@@ -885,27 +885,28 @@ static int pc_adjust_requested_freq(struct xe_guc_pc *pc)
 
 static int pc_set_mert_freq_cap(struct xe_guc_pc *pc)
 {
-	int ret = 0;
+	int ret;
 
-	if (XE_WA(pc_to_gt(pc), 22019338487)) {
-		/*
-		 * Get updated min/max and stash them.
-		 */
-		ret = xe_guc_pc_get_min_freq(pc, &pc->stashed_min_freq);
-		if (!ret)
-			ret = xe_guc_pc_get_max_freq(pc, &pc->stashed_max_freq);
-		if (ret)
-			return ret;
+	if (!XE_WA(pc_to_gt(pc), 22019338487))
+		return 0;
 
-		/*
-		 * Ensure min and max are bound by MERT_FREQ_CAP until driver loads.
-		 */
-		mutex_lock(&pc->freq_lock);
-		ret = pc_set_min_freq(pc, min(pc->rpe_freq, pc_max_freq_cap(pc)));
-		if (!ret)
-			ret = pc_set_max_freq(pc, min(pc->rp0_freq, pc_max_freq_cap(pc)));
-		mutex_unlock(&pc->freq_lock);
-	}
+	guard(mutex)(&pc->freq_lock);
+
+	/*
+	 * Get updated min/max and stash them.
+	 */
+	ret = xe_guc_pc_get_min_freq_locked(pc, &pc->stashed_min_freq);
+	if (!ret)
+		ret = xe_guc_pc_get_max_freq_locked(pc, &pc->stashed_max_freq);
+	if (ret)
+		return ret;
+
+	/*
+	 * Ensure min and max are bound by MERT_FREQ_CAP until driver loads.
+	 */
+	ret = pc_set_min_freq(pc, min(pc->rpe_freq, pc_max_freq_cap(pc)));
+	if (!ret)
+		ret = pc_set_max_freq(pc, min(pc->rp0_freq, pc_max_freq_cap(pc)));
 
 	return ret;
 }