drm/rockchip: A couple small fixes to psr

A few things that need tidying up, no functional changes.
Reviewed-by: NYakir Yang <ykk@rock-chips.com>
Signed-off-by: NSean Paul <seanpaul@chromium.org>

drivers/gpu/drm/rockchip/rockchip_drm_psr.c

@@ -62,27 +62,25 @@ static void psr_set_state_locked(struct psr_drv *psr, enum psr_state state)
 	 * Allowed finite state machine:
 	 *
 	 *   PSR_ENABLE  < = = = = = >  PSR_FLUSH
-	  *      | ^                        |
-	  *      | |                        |
-	  *      v |                        |
+	 *       | ^                        |
+	 *       | |                        |
+	 *       v |                        |
 	 *   PSR_DISABLE < - - - - - - - - -
 	 */
-
-	/* Forbid no state change */
 	if (state == psr->state)
 		return;
 
-	/* Forbid DISABLE change to FLUSH */
+	/* Requesting a flush when disabled is a noop */
 	if (state == PSR_FLUSH && psr->state == PSR_DISABLE)
 		return;
 
 	psr->state = state;
 
-	/* Allow but no need hardware change, just need assign the state */
+	/* Already disabled in flush, change the state, but not the hardware */
 	if (state == PSR_DISABLE && psr->state == PSR_FLUSH)
 		return;
 
-	/* Refact to hardware state change */
+	/* Actually commit the state change to hardware */
 	switch (psr->state) {
 	case PSR_ENABLE:
 		psr->set(psr->encoder, true);
@@ -109,10 +107,7 @@ static void psr_flush_handler(unsigned long data)
 	struct psr_drv *psr = (struct psr_drv *)data;
 	unsigned long flags;
 
-	if (!psr)
-		return;
-
-	/* State changed between flush time, then keep it */
+	/* If the state has changed since we initiated the flush, do nothing */
 	spin_lock_irqsave(&psr->lock, flags);
 	if (psr->state == PSR_FLUSH)
 		psr_set_state_locked(psr, PSR_ENABLE);