linux-kernel - [PATCH 5.18 328/339] drm/bridge: analogix_dp: Support PSR-exit to disable transition

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Message-Id: <20220613094936.693527072@linuxfoundation.org>
Date:   Mon, 13 Jun 2022 12:12:33 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Brian Norris <briannorris@...omium.org>,
        Sean Paul <seanpaul@...omium.org>,
        Douglas Anderson <dianders@...omium.org>
Subject: [PATCH 5.18 328/339] drm/bridge: analogix_dp: Support PSR-exit to disable transition

From: Brian Norris <briannorris@...omium.org>

commit ca871659ec1606d33b1e76de8d4cf924cf627e34 upstream.

Most eDP panel functions only work correctly when the panel is not in
self-refresh. In particular, analogix_dp_bridge_disable() tends to hit
AUX channel errors if the panel is in self-refresh.

Given the above, it appears that so far, this driver assumes that we are
never in self-refresh when it comes time to fully disable the bridge.
Prior to commit 846c7dfc1193 ("drm/atomic: Try to preserve the crtc
enabled state in drm_atomic_remove_fb, v2."), this tended to be true,
because we would automatically disable the pipe when framebuffers were
removed, and so we'd typically disable the bridge shortly after the last
display activity.

However, that is not guaranteed: an idle (self-refresh) display pipe may
be disabled, e.g., when switching CRTCs. We need to exit PSR first.

Stable notes: this is definitely a bugfix, and the bug has likely
existed in some form for quite a while. It may predate the "PSR helpers"
refactor, but the code looked very different before that, and it's
probably not worth rewriting the fix.

Cc: <stable@...r.kernel.org>
Fixes: 6c836d965bad ("drm/rockchip: Use the helpers for PSR")
Signed-off-by: Brian Norris <briannorris@...omium.org>
Reviewed-by: Sean Paul <seanpaul@...omium.org>
Signed-off-by: Douglas Anderson <dianders@...omium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220228122522.v2.1.I161904be17ba14526f78536ccd78b85818449b51@changeid
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c |   42 +++++++++++++++++++--
 1 file changed, 38 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -1269,6 +1269,25 @@ static int analogix_dp_bridge_attach(str
 }
 
 static
+struct drm_crtc *analogix_dp_get_old_crtc(struct analogix_dp_device *dp,
+					  struct drm_atomic_state *state)
+{
+	struct drm_encoder *encoder = dp->encoder;
+	struct drm_connector *connector;
+	struct drm_connector_state *conn_state;
+
+	connector = drm_atomic_get_old_connector_for_encoder(state, encoder);
+	if (!connector)
+		return NULL;
+
+	conn_state = drm_atomic_get_old_connector_state(state, connector);
+	if (!conn_state)
+		return NULL;
+
+	return conn_state->crtc;
+}
+
+static
 struct drm_crtc *analogix_dp_get_new_crtc(struct analogix_dp_device *dp,
 					  struct drm_atomic_state *state)
 {
@@ -1448,14 +1467,16 @@ analogix_dp_bridge_atomic_disable(struct
 {
 	struct drm_atomic_state *old_state = old_bridge_state->base.state;
 	struct analogix_dp_device *dp = bridge->driver_private;
-	struct drm_crtc *crtc;
+	struct drm_crtc *old_crtc, *new_crtc;
+	struct drm_crtc_state *old_crtc_state = NULL;
 	struct drm_crtc_state *new_crtc_state = NULL;
+	int ret;
 
-	crtc = analogix_dp_get_new_crtc(dp, old_state);
-	if (!crtc)
+	new_crtc = analogix_dp_get_new_crtc(dp, old_state);
+	if (!new_crtc)
 		goto out;
 
-	new_crtc_state = drm_atomic_get_new_crtc_state(old_state, crtc);
+	new_crtc_state = drm_atomic_get_new_crtc_state(old_state, new_crtc);
 	if (!new_crtc_state)
 		goto out;
 
@@ -1464,6 +1485,19 @@ analogix_dp_bridge_atomic_disable(struct
 		return;
 
 out:
+	old_crtc = analogix_dp_get_old_crtc(dp, old_state);
+	if (old_crtc) {
+		old_crtc_state = drm_atomic_get_old_crtc_state(old_state,
+							       old_crtc);
+
+		/* When moving from PSR to fully disabled, exit PSR first. */
+		if (old_crtc_state && old_crtc_state->self_refresh_active) {
+			ret = analogix_dp_disable_psr(dp);
+			if (ret)
+				DRM_ERROR("Failed to disable psr (%d)\n", ret);
+		}
+	}
+
 	analogix_dp_bridge_disable(bridge);
 }