drm/vkms: Reduce critical section

The spinlock composer_lock protects the variables crc_pending,
wb_pending, frame_start and frame_end, which are variables that are used
by the composer worker. There is no need to protect the wb_frame_info
information with a spinlock. Therefore, reduce the critical section of
the lock by removing the assignments to the wb_frame_info from the
critical section.
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Arthur Grillo <arthurgrillo@riseup.net>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230515135204.115393-2-mcanal@igalia.com

drivers/gpu/drm/vkms/vkms_writeback.c

@@ -142,11 +142,13 @@ static void vkms_wb_atomic_commit(struct drm_connector *conn,
 
 	spin_lock_irq(&output->composer_lock);
 	crtc_state->active_writeback = active_wb;
+	crtc_state->wb_pending = true;
+	spin_unlock_irq(&output->composer_lock);
+
 	wb_frame_info->offset = fb->offsets[0];
 	wb_frame_info->pitch = fb->pitches[0];
 	wb_frame_info->cpp = fb->format->cpp[0];
-	crtc_state->wb_pending = true;
-	spin_unlock_irq(&output->composer_lock);
+
 	drm_writeback_queue_job(wb_conn, connector_state);
 	active_wb->wb_write = get_line_to_frame_function(wb_format);
 	drm_rect_init(&wb_frame_info->src, 0, 0, crtc_width, crtc_height);