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Message-Id: <20250605171524.27222-4-aradhya.bhatia@linux.dev>
Date: Thu, 5 Jun 2025 22:45:23 +0530
From: Aradhya Bhatia <aradhya.bhatia@...ux.dev>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
Dmitry Baryshkov <lumag@...nel.org>,
Andrzej Hajda <andrzej.hajda@...el.com>,
Neil Armstrong <neil.armstrong@...aro.org>,
Robert Foss <rfoss@...nel.org>,
Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
Jonas Karlman <jonas@...boo.se>,
Jernej Skrabec <jernej.skrabec@...il.com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>,
Simona Vetter <simona@...ll.ch>
Cc: DRI Development List <dri-devel@...ts.freedesktop.org>,
Linux Kernel List <linux-kernel@...r.kernel.org>,
Nishanth Menon <nm@...com>,
Vignesh Raghavendra <vigneshr@...com>,
Devarsh Thakkar <devarsht@...com>,
Jayesh Choudhary <j-choudhary@...com>,
Aradhya Bhatia <aradhya.bhatia@...ux.dev>,
Alexander Sverdlin <alexander.sverdlin@...mens.com>
Subject: [PATCH v13 3/4] drm/atomic-helper: Re-order bridge chain pre-enable and post-disable
From: Aradhya Bhatia <a-bhatia1@...com>
Move the bridge pre_enable call before crtc enable, and the bridge
post_disable call after the crtc disable.
The sequence of enable after this patch will look like:
bridge[n]_pre_enable
...
bridge[1]_pre_enable
crtc_enable
encoder_enable
bridge[1]_enable
...
bridge[n]_enable
And, the disable sequence for the display pipeline will look like:
bridge[n]_disable
...
bridge[1]_disable
encoder_disable
crtc_disable
bridge[1]_post_disable
...
bridge[n]_post_disable
The definition of bridge pre_enable hook says that,
"The display pipe (i.e. clocks and timing signals) feeding this bridge
will not yet be running when this callback is called".
Since CRTC is also a source feeding the bridge, it should not be enabled
before the bridges in the pipeline are pre_enabled. Fix that by
re-ordering the sequence of bridge pre_enable and bridge post_disable.
While at it, update the drm bridge API documentation as well.
Acked-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@...e.de>
Tested-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@...mens.com>
Signed-off-by: Aradhya Bhatia <a-bhatia1@...com>
Signed-off-by: Aradhya Bhatia <aradhya.bhatia@...ux.dev>
---
drivers/gpu/drm/drm_atomic_helper.c | 8 +-
include/drm/drm_bridge.h | 249 ++++++++++++++++++++--------
2 files changed, 187 insertions(+), 70 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 539b7f072c72..2fe6c91910a1 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1336,9 +1336,9 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *state)
{
encoder_bridge_disable(dev, state);
- encoder_bridge_post_disable(dev, state);
-
crtc_disable(dev, state);
+
+ encoder_bridge_post_disable(dev, state);
}
/**
@@ -1674,10 +1674,10 @@ encoder_bridge_enable(struct drm_device *dev, struct drm_atomic_state *state)
void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
struct drm_atomic_state *state)
{
- crtc_enable(dev, state);
-
encoder_bridge_pre_enable(dev, state);
+ crtc_enable(dev, state);
+
encoder_bridge_enable(dev, state);
drm_atomic_helper_commit_writebacks(dev, state);
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 0af5db244db8..ecdeb90e5586 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -165,17 +165,33 @@ struct drm_bridge_funcs {
/**
* @disable:
*
- * This callback should disable the bridge. It is called right before
- * the preceding element in the display pipe is disabled. If the
- * preceding element is a bridge this means it's called before that
- * bridge's @disable vfunc. If the preceding element is a &drm_encoder
- * it's called right before the &drm_encoder_helper_funcs.disable,
- * &drm_encoder_helper_funcs.prepare or &drm_encoder_helper_funcs.dpms
- * hook.
+ * The @disable callback should disable the bridge.
*
* The bridge can assume that the display pipe (i.e. clocks and timing
* signals) feeding it is still running when this callback is called.
*
+ *
+ * If the preceding element is a &drm_bridge, then this is called before
+ * that bridge is disabled via one of:
+ *
+ * - &drm_bridge_funcs.disable
+ * - &drm_bridge_funcs.atomic_disable
+ *
+ * If the preceding element of the bridge is a display controller, then
+ * this callback is called before the encoder is disabled via one of:
+ *
+ * - &drm_encoder_helper_funcs.atomic_disable
+ * - &drm_encoder_helper_funcs.prepare
+ * - &drm_encoder_helper_funcs.disable
+ * - &drm_encoder_helper_funcs.dpms
+ *
+ * and the CRTC is disabled via one of:
+ *
+ * - &drm_crtc_helper_funcs.prepare
+ * - &drm_crtc_helper_funcs.atomic_disable
+ * - &drm_crtc_helper_funcs.disable
+ * - &drm_crtc_helper_funcs.dpms.
+ *
* The @disable callback is optional.
*
* NOTE:
@@ -188,17 +204,34 @@ struct drm_bridge_funcs {
/**
* @post_disable:
*
- * This callback should disable the bridge. It is called right after the
- * preceding element in the display pipe is disabled. If the preceding
- * element is a bridge this means it's called after that bridge's
- * @post_disable function. If the preceding element is a &drm_encoder
- * it's called right after the encoder's
- * &drm_encoder_helper_funcs.disable, &drm_encoder_helper_funcs.prepare
- * or &drm_encoder_helper_funcs.dpms hook.
- *
* The bridge must assume that the display pipe (i.e. clocks and timing
- * signals) feeding it is no longer running when this callback is
- * called.
+ * signals) feeding this bridge is no longer running when the
+ * @post_disable is called.
+ *
+ * This callback should perform all the actions required by the hardware
+ * after it has stopped receiving signals from the preceding element.
+ *
+ * If the preceding element is a &drm_bridge, then this is called after
+ * that bridge is post-disabled (unless marked otherwise by the
+ * @pre_enable_prev_first flag) via one of:
+ *
+ * - &drm_bridge_funcs.post_disable
+ * - &drm_bridge_funcs.atomic_post_disable
+ *
+ * If the preceding element of the bridge is a display controller, then
+ * this callback is called after the encoder is disabled via one of:
+ *
+ * - &drm_encoder_helper_funcs.atomic_disable
+ * - &drm_encoder_helper_funcs.prepare
+ * - &drm_encoder_helper_funcs.disable
+ * - &drm_encoder_helper_funcs.dpms
+ *
+ * and the CRTC is disabled via one of:
+ *
+ * - &drm_crtc_helper_funcs.prepare
+ * - &drm_crtc_helper_funcs.atomic_disable
+ * - &drm_crtc_helper_funcs.disable
+ * - &drm_crtc_helper_funcs.dpms
*
* The @post_disable callback is optional.
*
@@ -241,18 +274,30 @@ struct drm_bridge_funcs {
/**
* @pre_enable:
*
- * This callback should enable the bridge. It is called right before
- * the preceding element in the display pipe is enabled. If the
- * preceding element is a bridge this means it's called before that
- * bridge's @pre_enable function. If the preceding element is a
- * &drm_encoder it's called right before the encoder's
- * &drm_encoder_helper_funcs.enable, &drm_encoder_helper_funcs.commit or
- * &drm_encoder_helper_funcs.dpms hook.
- *
* The display pipe (i.e. clocks and timing signals) feeding this bridge
- * will not yet be running when this callback is called. The bridge must
- * not enable the display link feeding the next bridge in the chain (if
- * there is one) when this callback is called.
+ * will not yet be running when the @pre_enable is called.
+ *
+ * This callback should perform all the necessary actions to prepare the
+ * bridge to accept signals from the preceding element.
+ *
+ * If the preceding element is a &drm_bridge, then this is called before
+ * that bridge is pre-enabled (unless marked otherwise by
+ * @pre_enable_prev_first flag) via one of:
+ *
+ * - &drm_bridge_funcs.pre_enable
+ * - &drm_bridge_funcs.atomic_pre_enable
+ *
+ * If the preceding element of the bridge is a display controller, then
+ * this callback is called before the CRTC is enabled via one of:
+ *
+ * - &drm_crtc_helper_funcs.atomic_enable
+ * - &drm_crtc_helper_funcs.commit
+ *
+ * and the encoder is enabled via one of:
+ *
+ * - &drm_encoder_helper_funcs.atomic_enable
+ * - &drm_encoder_helper_funcs.enable
+ * - &drm_encoder_helper_funcs.commit
*
* The @pre_enable callback is optional.
*
@@ -266,19 +311,31 @@ struct drm_bridge_funcs {
/**
* @enable:
*
- * This callback should enable the bridge. It is called right after
- * the preceding element in the display pipe is enabled. If the
- * preceding element is a bridge this means it's called after that
- * bridge's @enable function. If the preceding element is a
- * &drm_encoder it's called right after the encoder's
- * &drm_encoder_helper_funcs.enable, &drm_encoder_helper_funcs.commit or
- * &drm_encoder_helper_funcs.dpms hook.
+ * The @enable callback should enable the bridge.
*
* The bridge can assume that the display pipe (i.e. clocks and timing
* signals) feeding it is running when this callback is called. This
* callback must enable the display link feeding the next bridge in the
* chain if there is one.
*
+ * If the preceding element is a &drm_bridge, then this is called after
+ * that bridge is enabled via one of:
+ *
+ * - &drm_bridge_funcs.enable
+ * - &drm_bridge_funcs.atomic_enable
+ *
+ * If the preceding element of the bridge is a display controller, then
+ * this callback is called after the CRTC is enabled via one of:
+ *
+ * - &drm_crtc_helper_funcs.atomic_enable
+ * - &drm_crtc_helper_funcs.commit
+ *
+ * and the encoder is enabled via one of:
+ *
+ * - &drm_encoder_helper_funcs.atomic_enable
+ * - &drm_encoder_helper_funcs.enable
+ * - drm_encoder_helper_funcs.commit
+ *
* The @enable callback is optional.
*
* NOTE:
@@ -291,17 +348,30 @@ struct drm_bridge_funcs {
/**
* @atomic_pre_enable:
*
- * This callback should enable the bridge. It is called right before
- * the preceding element in the display pipe is enabled. If the
- * preceding element is a bridge this means it's called before that
- * bridge's @atomic_pre_enable or @pre_enable function. If the preceding
- * element is a &drm_encoder it's called right before the encoder's
- * &drm_encoder_helper_funcs.atomic_enable hook.
- *
* The display pipe (i.e. clocks and timing signals) feeding this bridge
- * will not yet be running when this callback is called. The bridge must
- * not enable the display link feeding the next bridge in the chain (if
- * there is one) when this callback is called.
+ * will not yet be running when the @atomic_pre_enable is called.
+ *
+ * This callback should perform all the necessary actions to prepare the
+ * bridge to accept signals from the preceding element.
+ *
+ * If the preceding element is a &drm_bridge, then this is called before
+ * that bridge is pre-enabled (unless marked otherwise by
+ * @pre_enable_prev_first flag) via one of:
+ *
+ * - &drm_bridge_funcs.pre_enable
+ * - &drm_bridge_funcs.atomic_pre_enable
+ *
+ * If the preceding element of the bridge is a display controller, then
+ * this callback is called before the CRTC is enabled via one of:
+ *
+ * - &drm_crtc_helper_funcs.atomic_enable
+ * - &drm_crtc_helper_funcs.commit
+ *
+ * and the encoder is enabled via one of:
+ *
+ * - &drm_encoder_helper_funcs.atomic_enable
+ * - &drm_encoder_helper_funcs.enable
+ * - &drm_encoder_helper_funcs.commit
*
* The @atomic_pre_enable callback is optional.
*/
@@ -311,18 +381,31 @@ struct drm_bridge_funcs {
/**
* @atomic_enable:
*
- * This callback should enable the bridge. It is called right after
- * the preceding element in the display pipe is enabled. If the
- * preceding element is a bridge this means it's called after that
- * bridge's @atomic_enable or @enable function. If the preceding element
- * is a &drm_encoder it's called right after the encoder's
- * &drm_encoder_helper_funcs.atomic_enable hook.
+ * The @atomic_enable callback should enable the bridge.
*
* The bridge can assume that the display pipe (i.e. clocks and timing
* signals) feeding it is running when this callback is called. This
* callback must enable the display link feeding the next bridge in the
* chain if there is one.
*
+ * If the preceding element is a &drm_bridge, then this is called after
+ * that bridge is enabled via one of:
+ *
+ * - &drm_bridge_funcs.enable
+ * - &drm_bridge_funcs.atomic_enable
+ *
+ * If the preceding element of the bridge is a display controller, then
+ * this callback is called after the CRTC is enabled via one of:
+ *
+ * - &drm_crtc_helper_funcs.atomic_enable
+ * - &drm_crtc_helper_funcs.commit
+ *
+ * and the encoder is enabled via one of:
+ *
+ * - &drm_encoder_helper_funcs.atomic_enable
+ * - &drm_encoder_helper_funcs.enable
+ * - drm_encoder_helper_funcs.commit
+ *
* The @atomic_enable callback is optional.
*/
void (*atomic_enable)(struct drm_bridge *bridge,
@@ -330,16 +413,32 @@ struct drm_bridge_funcs {
/**
* @atomic_disable:
*
- * This callback should disable the bridge. It is called right before
- * the preceding element in the display pipe is disabled. If the
- * preceding element is a bridge this means it's called before that
- * bridge's @atomic_disable or @disable vfunc. If the preceding element
- * is a &drm_encoder it's called right before the
- * &drm_encoder_helper_funcs.atomic_disable hook.
+ * The @atomic_disable callback should disable the bridge.
*
* The bridge can assume that the display pipe (i.e. clocks and timing
* signals) feeding it is still running when this callback is called.
*
+ * If the preceding element is a &drm_bridge, then this is called before
+ * that bridge is disabled via one of:
+ *
+ * - &drm_bridge_funcs.disable
+ * - &drm_bridge_funcs.atomic_disable
+ *
+ * If the preceding element of the bridge is a display controller, then
+ * this callback is called before the encoder is disabled via one of:
+ *
+ * - &drm_encoder_helper_funcs.atomic_disable
+ * - &drm_encoder_helper_funcs.prepare
+ * - &drm_encoder_helper_funcs.disable
+ * - &drm_encoder_helper_funcs.dpms
+ *
+ * and the CRTC is disabled via one of:
+ *
+ * - &drm_crtc_helper_funcs.prepare
+ * - &drm_crtc_helper_funcs.atomic_disable
+ * - &drm_crtc_helper_funcs.disable
+ * - &drm_crtc_helper_funcs.dpms.
+ *
* The @atomic_disable callback is optional.
*/
void (*atomic_disable)(struct drm_bridge *bridge,
@@ -348,16 +447,34 @@ struct drm_bridge_funcs {
/**
* @atomic_post_disable:
*
- * This callback should disable the bridge. It is called right after the
- * preceding element in the display pipe is disabled. If the preceding
- * element is a bridge this means it's called after that bridge's
- * @atomic_post_disable or @post_disable function. If the preceding
- * element is a &drm_encoder it's called right after the encoder's
- * &drm_encoder_helper_funcs.atomic_disable hook.
- *
* The bridge must assume that the display pipe (i.e. clocks and timing
- * signals) feeding it is no longer running when this callback is
- * called.
+ * signals) feeding this bridge is no longer running when the
+ * @atomic_post_disable is called.
+ *
+ * This callback should perform all the actions required by the hardware
+ * after it has stopped receiving signals from the preceding element.
+ *
+ * If the preceding element is a &drm_bridge, then this is called after
+ * that bridge is post-disabled (unless marked otherwise by the
+ * @pre_enable_prev_first flag) via one of:
+ *
+ * - &drm_bridge_funcs.post_disable
+ * - &drm_bridge_funcs.atomic_post_disable
+ *
+ * If the preceding element of the bridge is a display controller, then
+ * this callback is called after the encoder is disabled via one of:
+ *
+ * - &drm_encoder_helper_funcs.atomic_disable
+ * - &drm_encoder_helper_funcs.prepare
+ * - &drm_encoder_helper_funcs.disable
+ * - &drm_encoder_helper_funcs.dpms
+ *
+ * and the CRTC is disabled via one of:
+ *
+ * - &drm_crtc_helper_funcs.prepare
+ * - &drm_crtc_helper_funcs.atomic_disable
+ * - &drm_crtc_helper_funcs.disable
+ * - &drm_crtc_helper_funcs.dpms
*
* The @atomic_post_disable callback is optional.
*/
--
2.34.1
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