This is a note to let you know that I've just added the patch titled
drm/bridge: Introduce pre_enable_prev_first to alter bridge init order
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-bridge-introduce-pre_enable_prev_first-to-alter-.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 3bcd91df87394559cf72a6c21eb473055aab1228
Author: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
Date: Mon Dec 5 17:33:26 2022 +0000
drm/bridge: Introduce pre_enable_prev_first to alter bridge init order
[ Upstream commit 4fb912e5e19075874379cfcf074d90bd51ebf8ea ]
DSI sink devices typically want the DSI host powered up and configured
before they are powered up. pre_enable is the place this would normally
happen, but they are called in reverse order from panel/connector towards
the encoder, which is the "wrong" order.
Add a new flag pre_enable_prev_first that any bridge can set
to swap the order of pre_enable (and post_disable) for that and the
immediately previous bridge.
Should the immediately previous bridge also set the
pre_enable_prev_first flag, the previous bridge to that will be called
before either of those which requested pre_enable_prev_first.
eg:
- Panel
- Bridge 1
- Bridge 2 pre_enable_prev_first
- Bridge 3
- Bridge 4 pre_enable_prev_first
- Bridge 5 pre_enable_prev_first
- Bridge 6
- Encoder
Would result in pre_enable's being called as Panel, Bridge 1, Bridge 3,
Bridge 2, Bridge 6, Bridge 5, Bridge 4, Encoder.
Signed-off-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
Tested-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
Reviewed-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20221205173328.1395350-5-dave.stevenson@xxxxxxxxxxxxxxx
Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>
Stable-dep-of: dd9e329af723 ("drm/bridge: ti-sn65dsi83: Fix enable/disable flow to meet spec")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 1545c50fd1c8f..7044e339a82cd 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -691,6 +691,25 @@ void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
}
EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
+static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,
+ struct drm_atomic_state *old_state)
+{
+ if (old_state && bridge->funcs->atomic_post_disable) {
+ struct drm_bridge_state *old_bridge_state;
+
+ old_bridge_state =
+ drm_atomic_get_old_bridge_state(old_state,
+ bridge);
+ if (WARN_ON(!old_bridge_state))
+ return;
+
+ bridge->funcs->atomic_post_disable(bridge,
+ old_bridge_state);
+ } else if (bridge->funcs->post_disable) {
+ bridge->funcs->post_disable(bridge);
+ }
+}
+
/**
* drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
* in the encoder chain
@@ -702,36 +721,86 @@ EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
* starting from the first bridge to the last. These are called after completing
* &drm_encoder_helper_funcs.atomic_disable
*
+ * If a bridge sets @pre_enable_prev_first, then the @post_disable for that
+ * bridge will be called before the previous one to reverse the @pre_enable
+ * calling direction.
+ *
* Note: the bridge passed should be the one closest to the encoder
*/
void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
struct drm_atomic_state *old_state)
{
struct drm_encoder *encoder;
+ struct drm_bridge *next, *limit;
if (!bridge)
return;
encoder = bridge->encoder;
+
list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
- if (bridge->funcs->atomic_post_disable) {
- struct drm_bridge_state *old_bridge_state;
+ limit = NULL;
+
+ if (!list_is_last(&bridge->chain_node, &encoder->bridge_chain)) {
+ next = list_next_entry(bridge, chain_node);
+
+ if (next->pre_enable_prev_first) {
+ /* next bridge had requested that prev
+ * was enabled first, so disabled last
+ */
+ limit = next;
+
+ /* Find the next bridge that has NOT requested
+ * prev to be enabled first / disabled last
+ */
+ list_for_each_entry_from(next, &encoder->bridge_chain,
+ chain_node) {
+ if (next->pre_enable_prev_first) {
+ next = list_prev_entry(next, chain_node);
+ limit = next;
+ break;
+ }
+ }
+
+ /* Call these bridges in reverse order */
+ list_for_each_entry_from_reverse(next, &encoder->bridge_chain,
+ chain_node) {
+ if (next == bridge)
+ break;
+
+ drm_atomic_bridge_call_post_disable(next,
+ old_state);
+ }
+ }
+ }
- old_bridge_state =
- drm_atomic_get_old_bridge_state(old_state,
- bridge);
- if (WARN_ON(!old_bridge_state))
- return;
+ drm_atomic_bridge_call_post_disable(bridge, old_state);
- bridge->funcs->atomic_post_disable(bridge,
- old_bridge_state);
- } else if (bridge->funcs->post_disable) {
- bridge->funcs->post_disable(bridge);
- }
+ if (limit)
+ /* Jump all bridges that we have already post_disabled */
+ bridge = limit;
}
}
EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
+static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,
+ struct drm_atomic_state *old_state)
+{
+ if (old_state && bridge->funcs->atomic_pre_enable) {
+ struct drm_bridge_state *old_bridge_state;
+
+ old_bridge_state =
+ drm_atomic_get_old_bridge_state(old_state,
+ bridge);
+ if (WARN_ON(!old_bridge_state))
+ return;
+
+ bridge->funcs->atomic_pre_enable(bridge, old_bridge_state);
+ } else if (bridge->funcs->pre_enable) {
+ bridge->funcs->pre_enable(bridge);
+ }
+}
+
/**
* drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
* the encoder chain
@@ -743,32 +812,60 @@ EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
* starting from the last bridge to the first. These are called before calling
* &drm_encoder_helper_funcs.atomic_enable
*
+ * If a bridge sets @pre_enable_prev_first, then the pre_enable for the
+ * prev bridge will be called before pre_enable of this bridge.
+ *
* Note: the bridge passed should be the one closest to the encoder
*/
void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
struct drm_atomic_state *old_state)
{
struct drm_encoder *encoder;
- struct drm_bridge *iter;
+ struct drm_bridge *iter, *next, *limit;
if (!bridge)
return;
encoder = bridge->encoder;
+
list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
- if (iter->funcs->atomic_pre_enable) {
- struct drm_bridge_state *old_bridge_state;
+ if (iter->pre_enable_prev_first) {
+ next = iter;
+ limit = bridge;
+ list_for_each_entry_from_reverse(next,
+ &encoder->bridge_chain,
+ chain_node) {
+ if (next == bridge)
+ break;
+
+ if (!next->pre_enable_prev_first) {
+ /* Found first bridge that does NOT
+ * request prev to be enabled first
+ */
+ limit = list_prev_entry(next, chain_node);
+ break;
+ }
+ }
+
+ list_for_each_entry_from(next, &encoder->bridge_chain, chain_node) {
+ /* Call requested prev bridge pre_enable
+ * in order.
+ */
+ if (next == iter)
+ /* At the first bridge to request prev
+ * bridges called first.
+ */
+ break;
+
+ drm_atomic_bridge_call_pre_enable(next, old_state);
+ }
+ }
- old_bridge_state =
- drm_atomic_get_old_bridge_state(old_state,
- iter);
- if (WARN_ON(!old_bridge_state))
- return;
+ drm_atomic_bridge_call_pre_enable(iter, old_state);
- iter->funcs->atomic_pre_enable(iter, old_bridge_state);
- } else if (iter->funcs->pre_enable) {
- iter->funcs->pre_enable(iter);
- }
+ if (iter->pre_enable_prev_first)
+ /* Jump all bridges that we have already pre_enabled */
+ iter = limit;
if (iter == bridge)
break;
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 288c6feda5de2..6b656ea23b964 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -768,6 +768,14 @@ struct drm_bridge {
* modes.
*/
bool interlace_allowed;
+ /**
+ * @pre_enable_prev_first: The bridge requires that the prev
+ * bridge @pre_enable function is called before its @pre_enable,
+ * and conversely for post_disable. This is most frequently a
+ * requirement for DSI devices which need the host to be initialised
+ * before the peripheral.
+ */
+ bool pre_enable_prev_first;
/**
* @ddc: Associated I2C adapter for DDC access, if any.
*/
