accel/ivpu: Fix fw log printing

  - Fix empty log detection that couldn't work without read_wrap_count
  - Start printing wrapped log from correct position (log_start)
  - Properly handle logs that are wrapped multiple times in reference
    to reader position
  - Don't add a newline when log buffer is wrapped
  - Always add a newline after printing a log buffer in case log does
    not end with one

Reviewed-by: Tomasz Rusinowicz <tomasz.rusinowicz@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240930195322.461209-6-jacek.lawrynowicz@linux.intel.com
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>

drivers/accel/ivpu/ivpu_fw_log.c

@@ -87,31 +87,37 @@ static void fw_log_print_lines(char *buffer, u32 size, struct drm_printer *p)
 	}
 	line[index] = 0;
 	if (index != 0)
-		drm_printf(p, "%s\n", line);
+		drm_printf(p, "%s", line);
 }
 
 static void fw_log_print_buffer(struct vpu_tracing_buffer_header *log, const char *prefix,
 				bool only_new_msgs, struct drm_printer *p)
 {
 	char *log_data = (void *)log + log->header_size;
 	u32 data_size = log->size - log->header_size;
-	u32 log_start = log->read_index;
-	u32 log_end = log->write_index;
+	u32 log_start = only_new_msgs ? READ_ONCE(log->read_index) : 0;
+	u32 log_end = READ_ONCE(log->write_index);
 
-	if (!(log->write_index || log->wrap_count) ||
-	    (log->write_index == log->read_index && only_new_msgs)) {
-		drm_printf(p, "==== %s \"%s\" log empty ====\n", prefix, log->name);
-		return;
+	if (log->wrap_count == log->read_wrap_count) {
+		if (log_end <= log_start) {
+			drm_printf(p, "==== %s \"%s\" log empty ====\n", prefix, log->name);
+			return;
+		}
+	} else if (log->wrap_count == log->read_wrap_count + 1) {
+		if (log_end > log_start)
+			log_start = log_end;
+	} else {
+		log_start = log_end;
 	}
 
 	drm_printf(p, "==== %s \"%s\" log start ====\n", prefix, log->name);
-	if (log->write_index > log->read_index) {
+	if (log_end > log_start) {
 		fw_log_print_lines(log_data + log_start, log_end - log_start, p);
 	} else {
-		fw_log_print_lines(log_data + log_end, data_size - log_end, p);
+		fw_log_print_lines(log_data + log_start, data_size - log_start, p);
 		fw_log_print_lines(log_data, log_end, p);
 	}
-	drm_printf(p, "\x1b[0m");
+	drm_printf(p, "\n\x1b[0m"); /* add new line and clear formatting */
 	drm_printf(p, "==== %s \"%s\" log end   ====\n", prefix, log->name);
 }
 
@@ -135,14 +141,19 @@ void ivpu_fw_log_print(struct ivpu_device *vdev, bool only_new_msgs, struct drm_
 void ivpu_fw_log_mark_read(struct ivpu_device *vdev)
 {
 	struct vpu_tracing_buffer_header *log;
-	u32 next = 0;
+	u32 next;
 
-	while (fw_log_from_bo(vdev, vdev->fw->mem_log_crit, &next, &log) == 0)
-		log->read_index = log->write_index;
+	next = 0;
+	while (fw_log_from_bo(vdev, vdev->fw->mem_log_crit, &next, &log) == 0) {
+		log->read_index = READ_ONCE(log->write_index);
+		log->read_wrap_count = READ_ONCE(log->wrap_count);
+	}
 
 	next = 0;
-	while (fw_log_from_bo(vdev, vdev->fw->mem_log_verb, &next, &log) == 0)
-		log->read_index = log->write_index;
+	while (fw_log_from_bo(vdev, vdev->fw->mem_log_verb, &next, &log) == 0) {
+		log->read_index = READ_ONCE(log->write_index);
+		log->read_wrap_count = READ_ONCE(log->wrap_count);
+	}
 }
 
 void ivpu_fw_log_reset(struct ivpu_device *vdev)
@@ -151,10 +162,14 @@ void ivpu_fw_log_reset(struct ivpu_device *vdev)
 	u32 next;
 
 	next = 0;
-	while (fw_log_from_bo(vdev, vdev->fw->mem_log_crit, &next, &log) == 0)
+	while (fw_log_from_bo(vdev, vdev->fw->mem_log_crit, &next, &log) == 0) {
 		log->read_index = 0;
+		log->read_wrap_count = 0;
+	}
 
 	next = 0;
-	while (fw_log_from_bo(vdev, vdev->fw->mem_log_verb, &next, &log) == 0)
+	while (fw_log_from_bo(vdev, vdev->fw->mem_log_verb, &next, &log) == 0) {
 		log->read_index = 0;
+		log->read_wrap_count = 0;
+	}
 }