linux-kernel - [PATCH] drm/atomic: Check new_crtc_state->active to determine if CRTC needs disable in self refresh mode

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Date:   Thu, 30 Dec 2021 12:06:26 +0800
From:   Liu Ying <victor.liu@....com>
To:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     linux-imx@....com, Sean Paul <seanpaul@...omium.org>,
        Rob Clark <robdclark@...omium.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Subject: [PATCH] drm/atomic: Check new_crtc_state->active to determine if CRTC needs disable in self refresh mode

Actual hardware state of CRTC is controlled by the member 'active' in
struct drm_crtc_state instead of the member 'enable', according to the
kernel doc of the member 'enable'.  In fact, the drm client modeset
and atomic helpers are using the member 'active' to do the control.

Referencing the member 'enable' of new_crtc_state, the function
crtc_needs_disable() may fail to reflect if CRTC needs disable in
self refresh mode, e.g., when the framebuffer emulation will be blanked
through the client modeset helper with the next commit, the member
'enable' of new_crtc_state is still true while the member 'active' is
false, hence the relevant potential encoder and bridges won't be disabled.

So, let's check new_crtc_state->active to determine if CRTC needs disable
in self refresh mode instead of new_crtc_state->enable.

Fixes: 1452c25b0e60 ("drm: Add helpers to kick off self refresh mode in drivers")
Cc: Sean Paul <seanpaul@...omium.org>
Cc: Rob Clark <robdclark@...omium.org>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Cc: Maxime Ripard <mripard@...nel.org>
Cc: Thomas Zimmermann <tzimmermann@...e.de>
Cc: David Airlie <airlied@...ux.ie>
Cc: Daniel Vetter <daniel@...ll.ch>
Signed-off-by: Liu Ying <victor.liu@....com>
---
 drivers/gpu/drm/drm_atomic_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index a7a05e1e26bb..9603193d2fa1 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1016,7 +1016,7 @@ crtc_needs_disable(struct drm_crtc_state *old_state,
 	 * it's in self refresh mode and needs to be fully disabled.
 	 */
 	return old_state->active ||
-	       (old_state->self_refresh_active && !new_state->enable) ||
+	       (old_state->self_refresh_active && !new_state->active) ||
 	       new_state->self_refresh_active;
 }

-- 
2.25.1