FAILED: patch "[PATCH] drm/atomic: Force bridge self-refresh-exit on CRTC switch" failed to apply to 5.4-stable tree

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e54a4424925a27ed94dff046db3ce5caf4b1e748 Mon Sep 17 00:00:00 2001
From: Brian Norris <[email protected]>
Date: Mon, 28 Feb 2022 12:25:32 -0800
Subject: [PATCH] drm/atomic: Force bridge self-refresh-exit on CRTC switch

It's possible to change which CRTC is in use for a given connector/encoder/bridge while we're in self-refresh without fully disabling the connector/encoder/bridge along the way. This can confuse the bridge encoder/bridge, because
(a) it needs to track the SR state (trying to perform "active" operations while the panel is still in SR can be Bad(TM)); and
(b) it tracks the SR state via the CRTC state (and after the switch, the previous SR state is lost).

Thus, we need to either somehow carry the self-refresh state over to the new CRTC, or else force an encoder/bridge self-refresh transition during such a switch.

I choose the latter, so we disable the encoder (and exit PSR) before attaching it to the new CRTC (where we can continue to assume a clean (non-self-refresh) state).

This fixes PSR issues seen on Rockchip RK3399 systems with drivers/gpu/drm/bridge/analogix/analogix_dp_core.c.

Change in v2:

- Drop "->enable" condition; this could possibly be "->active" to reflect the intended hardware state, but it also is a little over-specific. We want to make a transition through "disabled" any time we're exiting PSR at the same time as a CRTC switch. (Thanks Liu Ying)

index 9603193d2fa1..987e4b212e9f 100644
@@ -1011,9 +1011,19 @@ crtc_needs_disable(struct drm_crtc_state *old_state,
 		return drm_atomic_crtc_effectively_active(old_state);
 
 	/*
-	 * We need to run through the crtc_funcs->disable() function if the CRTC
-	 * is currently on, if it's transitioning to self refresh mode, or if
-	 * it's in self refresh mode and needs to be fully disabled.
+	 * We need to disable bridge(s) and CRTC if we're transitioning out of
+	 * self-refresh and changing CRTCs at the same time, because the
+	 * bridge tracks self-refresh status via CRTC state.
+	 */
+	if (old_state->self_refresh_active &&
+	    old_state->crtc != new_state->crtc)
+		return true;
+
+	/*
+	 * We also need to run through the crtc_funcs->disable() function if
+	 * the CRTC is currently on, if it's transitioning to self refresh
+	 * mode, or if it's in self refresh mode and needs to be fully
+	 * disabled.
 	 */
 	return old_state->active ||
 	       (old_state->self_refresh_active && !new_state->active) ||