drm/gma500: Fix SDVO command debug printing

At some point the DRM printers started adding a newline after each
print. This caused SDVO command debug printing to look weird. Fix this
by using snprintf to print into a buffer which can be printed as a whole
by DRM_DEBUG_KMS(). Code is heavily inspired by i915.
Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220610130925.8650-1-patrik.r.jakobsson@gmail.com

drivers/gpu/drm/gma500/psb_intel_sdvo.c

@@ -400,26 +400,38 @@ static const struct _sdvo_cmd_name {
 #define IS_SDVOB(reg)	(reg == SDVOB)
 #define SDVO_NAME(svdo) (IS_SDVOB((svdo)->sdvo_reg) ? "SDVOB" : "SDVOC")
 
-static void psb_intel_sdvo_debug_write(struct psb_intel_sdvo *psb_intel_sdvo, u8 cmd,
-				   const void *args, int args_len)
+static void psb_intel_sdvo_debug_write(struct psb_intel_sdvo *psb_intel_sdvo,
+				       u8 cmd, const void *args, int args_len)
 {
-	int i;
+	struct drm_device *dev = psb_intel_sdvo->base.base.dev;
+	int i, pos = 0;
+	char buffer[73];
+
+#define BUF_PRINT(args...) \
+	pos += snprintf(buffer + pos, max_t(int, sizeof(buffer) - pos, 0), args)
+
+	for (i = 0; i < args_len; i++) {
+		BUF_PRINT("%02X ", ((u8 *)args)[i]);
+	}
+
+	for (; i < 8; i++) {
+		BUF_PRINT("   ");
+	}
 
-	DRM_DEBUG_KMS("%s: W: %02X ",
-				SDVO_NAME(psb_intel_sdvo), cmd);
-	for (i = 0; i < args_len; i++)
-		DRM_DEBUG_KMS("%02X ", ((u8 *)args)[i]);
-	for (; i < 8; i++)
-		DRM_DEBUG_KMS("   ");
 	for (i = 0; i < ARRAY_SIZE(sdvo_cmd_names); i++) {
 		if (cmd == sdvo_cmd_names[i].cmd) {
-			DRM_DEBUG_KMS("(%s)", sdvo_cmd_names[i].name);
+			BUF_PRINT("(%s)", sdvo_cmd_names[i].name);
 			break;
 		}
 	}
+
 	if (i == ARRAY_SIZE(sdvo_cmd_names))
-		DRM_DEBUG_KMS("(%02X)", cmd);
-	DRM_DEBUG_KMS("\n");
+		BUF_PRINT("(%02X)", cmd);
+
+	drm_WARN_ON(dev, pos >= sizeof(buffer) - 1);
+#undef BUF_PRINT
+
+	DRM_DEBUG_KMS("%s: W: %02X %s\n", SDVO_NAME(psb_intel_sdvo), cmd, buffer);
 }
 
 static const char *cmd_status_names[] = {
@@ -490,13 +502,13 @@ static bool psb_intel_sdvo_write_cmd(struct psb_intel_sdvo *psb_intel_sdvo, u8 c
 }
 
 static bool psb_intel_sdvo_read_response(struct psb_intel_sdvo *psb_intel_sdvo,
-				     void *response, int response_len)
+					 void *response, int response_len)
 {
+	struct drm_device *dev = psb_intel_sdvo->base.base.dev;
+	char buffer[73];
+	int i, pos = 0;
 	u8 retry = 5;
 	u8 status;
-	int i;
-
-	DRM_DEBUG_KMS("%s: R: ", SDVO_NAME(psb_intel_sdvo));
 
 	/*
 	 * The documentation states that all commands will be
@@ -520,10 +532,13 @@ static bool psb_intel_sdvo_read_response(struct psb_intel_sdvo *psb_intel_sdvo,
 			goto log_fail;
 	}
 
+#define BUF_PRINT(args...) \
+	pos += snprintf(buffer + pos, max_t(int, sizeof(buffer) - pos, 0), args)
+
 	if (status <= SDVO_CMD_STATUS_SCALING_NOT_SUPP)
-		DRM_DEBUG_KMS("(%s)", cmd_status_names[status]);
+		BUF_PRINT("(%s)", cmd_status_names[status]);
 	else
-		DRM_DEBUG_KMS("(??? %d)", status);
+		BUF_PRINT("(??? %d)", status);
 
 	if (status != SDVO_CMD_STATUS_SUCCESS)
 		goto log_fail;
@@ -534,13 +549,18 @@ static bool psb_intel_sdvo_read_response(struct psb_intel_sdvo *psb_intel_sdvo,
 					  SDVO_I2C_RETURN_0 + i,
 					  &((u8 *)response)[i]))
 			goto log_fail;
-		DRM_DEBUG_KMS(" %02X", ((u8 *)response)[i]);
+		BUF_PRINT(" %02X", ((u8 *)response)[i]);
 	}
-	DRM_DEBUG_KMS("\n");
+
+	drm_WARN_ON(dev, pos >= sizeof(buffer) - 1);
+#undef BUF_PRINT
+
+	DRM_DEBUG_KMS("%s: R: %s\n", SDVO_NAME(psb_intel_sdvo), buffer);
 	return true;
 
 log_fail:
-	DRM_DEBUG_KMS("... failed\n");
+	DRM_DEBUG_KMS("%s: R: ... failed %s\n",
+		      SDVO_NAME(psb_intel_sdvo), buffer);
 	return false;
 }