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@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;