[PATCH V2 2/4] drm/bridge: Introduce pre_enable_upstream_first to alter bridge init order
Dave Stevenson
dave.stevenson at raspberrypi.com
Fri Mar 4 15:17:57 UTC 2022
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_upstream_first that any bridge can set
to swap the order of pre_enable (and post_disable) for that and the
immediately upstream bridge.
Should the immediately upstream bridge also set the
pre_enable_upstream_first flag, the bridge upstream of that will be called
before either of those which requested pre_enable_upstream_first.
eg:
- Panel
- Bridge 1
- Bridge 2 pre_enable_upstream_first
- Bridge 3
- Bridge 4 pre_enable_upstream_first
- Bridge 5 pre_enable_upstream_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 at raspberrypi.com>
---
drivers/gpu/drm/drm_bridge.c | 116 +++++++++++++++++++++++++++++++++----------
include/drm/drm_bridge.h | 8 +++
2 files changed, 98 insertions(+), 26 deletions(-)
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 198fd471a488..70b513f5ce0d 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -523,6 +523,10 @@ EXPORT_SYMBOL(drm_bridge_chain_disable);
* encoder chain, starting from the first bridge to the last. These are called
* after completing the encoder's prepare op.
*
+ * If a bridge sets @pre_enable_upstream_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_bridge_chain_post_disable(struct drm_bridge *bridge)
@@ -569,6 +573,9 @@ EXPORT_SYMBOL(drm_bridge_chain_mode_set);
* chain, starting from the last bridge to the first. These are called
* before calling the encoder's commit op.
*
+ * If a bridge sets @pre_enable_upstream_first, then the @pre_enable for the
+ * previous bridge will be called before @pre_enable of this bridge.
+ *
* Note: the bridge passed should be the one closest to the encoder
*/
void drm_bridge_chain_pre_enable(struct drm_bridge *bridge)
@@ -645,6 +652,25 @@ 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
@@ -655,6 +681,9 @@ EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
* &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
* 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_upstream_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
*/
@@ -662,30 +691,55 @@ void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
struct drm_atomic_state *old_state)
{
struct drm_encoder *encoder;
+ struct drm_bridge *prev, *tmp;
if (!bridge)
return;
encoder = bridge->encoder;
- list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
- 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;
+ list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
+ if (!list_is_last(&bridge->chain_node, &encoder->bridge_chain) &&
+ list_next_entry(bridge, chain_node)->pre_enable_upstream_first)
+ /* Skip bridges where the downstream bridge wanted
+ * pre_enable after / post_disable before the upstream
+ * bridge.
+ */
+ continue;
- bridge->funcs->atomic_post_disable(bridge,
- old_bridge_state);
- } else if (bridge->funcs->post_disable) {
- bridge->funcs->post_disable(bridge);
- }
+ /* Call this bridge and any skipped ones in reverse order */
+ tmp = bridge;
+ do {
+ prev = tmp;
+ drm_atomic_bridge_call_post_disable(tmp, old_state);
+ if (tmp == list_first_entry(&encoder->bridge_chain,
+ struct drm_bridge, chain_node))
+ tmp = NULL;
+ else
+ tmp = list_prev_entry(tmp, chain_node);
+ } while (tmp && prev->pre_enable_upstream_first);
}
}
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
@@ -697,32 +751,42 @@ 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_upstream_first, then the pre_enable for the
+ * upstream 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, *tmp;
if (!bridge)
return;
encoder = bridge->encoder;
- list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
- if (old_state && iter->funcs->atomic_pre_enable) {
- struct drm_bridge_state *old_bridge_state;
- old_bridge_state =
- drm_atomic_get_old_bridge_state(old_state,
- iter);
- if (WARN_ON(!old_bridge_state))
- return;
+ list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
+ if (iter->pre_enable_upstream_first && iter != bridge)
+ /* Skip bridges which want the upstream pre_enable
+ * called before their pre_enable.
+ */
+ continue;
- iter->funcs->atomic_pre_enable(iter, old_bridge_state);
- } else if (iter->funcs->pre_enable) {
- iter->funcs->pre_enable(iter);
- }
+ tmp = iter;
+ do {
+ /* Work forward through the current bridge, and any
+ * that had been skipped.
+ */
+ drm_atomic_bridge_call_pre_enable(tmp, old_state);
+ if (tmp == list_last_entry(&encoder->bridge_chain,
+ struct drm_bridge,
+ chain_node))
+ tmp = NULL;
+ else
+ tmp = list_next_entry(tmp, chain_node);
+ } while (tmp && tmp->pre_enable_upstream_first);
if (iter == bridge)
break;
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index f27b4060faa2..cf1fb3ad7054 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -769,6 +769,14 @@ struct drm_bridge {
*/
bool interlace_allowed;
/**
+ * @pre_enable_upstream_first: The bridge requires that the upstream
+ * 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_upstream_first;
+ /**
* @ddc: Associated I2C adapter for DDC access, if any.
*/
struct i2c_adapter *ddc;
--
2.7.4
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