On Tue, Jan 14, 2025 at 11:26:25AM +0530, Aradhya Bhatia wrote:
> 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.
The patch contains both refactoring of the corresponding functions and
changing of the order. Please split it into two separate commits.
>
> Signed-off-by: Aradhya Bhatia <a-bhatia1@xxxxxx>
> Signed-off-by: Aradhya Bhatia <aradhya.bhatia@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_atomic_helper.c | 300 +++++++++++++++++-----------
> 1 file changed, 181 insertions(+), 119 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index 5186d2114a50..ad6290a4a528 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -74,6 +74,12 @@
> * also shares the &struct drm_plane_helper_funcs function table with the plane
> * helpers.
> */
> +
> +enum bridge_chain_operation_type {
> + DRM_BRIDGE_PRE_ENABLE_OR_POST_DISABLE,
> + DRM_BRIDGE_ENABLE_OR_DISABLE,
> +};
> +
I have mixed feelings towards this approach. I doubt that it actually
helps. Would you mind replacing it with just 'bool pre_enable' / 'bool
post_disable' arguments?
> static void
> drm_atomic_helper_plane_changed(struct drm_atomic_state *state,
> struct drm_plane_state *old_plane_state,
> @@ -1122,74 +1128,12 @@ crtc_needs_disable(struct drm_crtc_state *old_state,
> }
>
> static void
> -disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
> +crtc_disable(struct drm_device *dev, struct drm_atomic_state *old_state)
> {
> - struct drm_connector *connector;
> - struct drm_connector_state *old_conn_state, *new_conn_state;
> struct drm_crtc *crtc;
> struct drm_crtc_state *old_crtc_state, *new_crtc_state;
> int i;
>
> - for_each_oldnew_connector_in_state(old_state, connector, old_conn_state, new_conn_state, i) {
> - const struct drm_encoder_helper_funcs *funcs;
> - struct drm_encoder *encoder;
> - struct drm_bridge *bridge;
> -
> - /*
> - * Shut down everything that's in the changeset and currently
> - * still on. So need to check the old, saved state.
> - */
> - if (!old_conn_state->crtc)
> - continue;
> -
> - old_crtc_state = drm_atomic_get_old_crtc_state(old_state, old_conn_state->crtc);
> -
> - if (new_conn_state->crtc)
> - new_crtc_state = drm_atomic_get_new_crtc_state(
> - old_state,
> - new_conn_state->crtc);
> - else
> - new_crtc_state = NULL;
> -
> - if (!crtc_needs_disable(old_crtc_state, new_crtc_state) ||
> - !drm_atomic_crtc_needs_modeset(old_conn_state->crtc->state))
> - continue;
> -
> - encoder = old_conn_state->best_encoder;
> -
> - /* We shouldn't get this far if we didn't previously have
> - * an encoder.. but WARN_ON() rather than explode.
> - */
> - if (WARN_ON(!encoder))
> - continue;
> -
> - funcs = encoder->helper_private;
> -
> - drm_dbg_atomic(dev, "disabling [ENCODER:%d:%s]\n",
> - encoder->base.id, encoder->name);
> -
> - /*
> - * Each encoder has at most one connector (since we always steal
> - * it away), so we won't call disable hooks twice.
> - */
> - bridge = drm_bridge_chain_get_first_bridge(encoder);
> - drm_atomic_bridge_chain_disable(bridge, old_state);
> -
> - /* Right function depends upon target state. */
> - if (funcs) {
> - if (funcs->atomic_disable)
> - funcs->atomic_disable(encoder, old_state);
> - else if (new_conn_state->crtc && funcs->prepare)
> - funcs->prepare(encoder);
> - else if (funcs->disable)
> - funcs->disable(encoder);
> - else if (funcs->dpms)
> - funcs->dpms(encoder, DRM_MODE_DPMS_OFF);
> - }
> -
> - drm_atomic_bridge_chain_post_disable(bridge, old_state);
> - }
> -
> for_each_oldnew_crtc_in_state(old_state, crtc, old_crtc_state, new_crtc_state, i) {
> const struct drm_crtc_helper_funcs *funcs;
> int ret;
> @@ -1206,7 +1150,6 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
> drm_dbg_atomic(dev, "disabling [CRTC:%d:%s]\n",
> crtc->base.id, crtc->name);
>
> -
Irrelevant, please drop.
> /* Right function depends upon target state. */
> if (new_crtc_state->enable && funcs->prepare)
> funcs->prepare(crtc);
> @@ -1236,6 +1179,97 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
> }
> }
>
> +static void
> +encoder_bridge_chain_disable(struct drm_device *dev, struct drm_atomic_state *old_state,
> + enum bridge_chain_operation_type op_type)
> +{
> + struct drm_connector *connector;
> + struct drm_connector_state *old_conn_state, *new_conn_state;
> + struct drm_crtc_state *old_crtc_state, *new_crtc_state;
> + int i;
> +
> + for_each_oldnew_connector_in_state(old_state, connector, old_conn_state, new_conn_state, i) {
> + const struct drm_encoder_helper_funcs *funcs;
> + struct drm_encoder *encoder;
> + struct drm_bridge *bridge;
> +
> + /*
> + * Shut down everything that's in the changeset and currently
> + * still on. So need to check the old, saved state.
> + */
> + if (!old_conn_state->crtc)
> + continue;
> +
> + old_crtc_state = drm_atomic_get_old_crtc_state(old_state, old_conn_state->crtc);
> +
> + if (new_conn_state->crtc)
> + new_crtc_state = drm_atomic_get_new_crtc_state(
> + old_state,
> + new_conn_state->crtc);
> + else
> + new_crtc_state = NULL;
> +
> + if (!crtc_needs_disable(old_crtc_state, new_crtc_state) ||
> + !drm_atomic_crtc_needs_modeset(old_conn_state->crtc->state))
> + continue;
> +
> + encoder = old_conn_state->best_encoder;
> +
> + /* We shouldn't get this far if we didn't previously have
> + * an encoder.. but WARN_ON() rather than explode.
> + */
> + if (WARN_ON(!encoder))
> + continue;
> +
> + /*
> + * Each encoder has at most one connector (since we always steal
> + * it away), so we won't call disable hooks twice.
> + */
> + bridge = drm_bridge_chain_get_first_bridge(encoder);
> +
> + switch (op_type) {
> + case DRM_BRIDGE_ENABLE_OR_DISABLE:
> + funcs = encoder->helper_private;
> +
> + drm_dbg_atomic(dev, "disabling [ENCODER:%d:%s]\n",
> + encoder->base.id, encoder->name);
> +
> + drm_atomic_bridge_chain_disable(bridge, old_state);
> +
> + /* Right function depends upon target state. */
> + if (funcs) {
> + if (funcs->atomic_disable)
> + funcs->atomic_disable(encoder, old_state);
> + else if (new_conn_state->crtc && funcs->prepare)
> + funcs->prepare(encoder);
> + else if (funcs->disable)
> + funcs->disable(encoder);
> + else if (funcs->dpms)
> + funcs->dpms(encoder, DRM_MODE_DPMS_OFF);
> + }
> +
> + break;
> +
> + case DRM_BRIDGE_PRE_ENABLE_OR_POST_DISABLE:
> + drm_atomic_bridge_chain_post_disable(bridge, old_state);
> + break;
> +
> + default:
> + drm_err(dev, "Unrecognized Encoder/Bridge operation (%d).\n", op_type);
> + }
> + }
> +}
> +
> +static void
> +disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
> +{
> + encoder_bridge_chain_disable(dev, old_state, DRM_BRIDGE_ENABLE_OR_DISABLE);
> +
> + crtc_disable(dev, old_state);
> +
> + encoder_bridge_chain_disable(dev, old_state, DRM_BRIDGE_PRE_ENABLE_OR_POST_DISABLE);
> +}
> +
> /**
> * drm_atomic_helper_update_legacy_modeset_state - update legacy modeset state
> * @dev: DRM device
> @@ -1445,28 +1479,69 @@ static void drm_atomic_helper_commit_writebacks(struct drm_device *dev,
> }
> }
>
> -/**
> - * drm_atomic_helper_commit_modeset_enables - modeset commit to enable outputs
> - * @dev: DRM device
> - * @old_state: atomic state object with old state structures
> - *
> - * This function enables all the outputs with the new configuration which had to
> - * be turned off for the update.
> - *
> - * For compatibility with legacy CRTC helpers this should be called after
> - * drm_atomic_helper_commit_planes(), which is what the default commit function
> - * does. But drivers with different needs can group the modeset commits together
> - * and do the plane commits at the end. This is useful for drivers doing runtime
> - * PM since planes updates then only happen when the CRTC is actually enabled.
> - */
> -void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
> - struct drm_atomic_state *old_state)
> +static void
> +encoder_bridge_chain_enable(struct drm_device *dev, struct drm_atomic_state *old_state,
> + enum bridge_chain_operation_type op_type)
> +{
> + struct drm_connector *connector;
> + struct drm_connector_state *new_conn_state;
> + int i;
> +
> + for_each_new_connector_in_state(old_state, connector, new_conn_state, i) {
> + const struct drm_encoder_helper_funcs *funcs;
> + struct drm_encoder *encoder;
> + struct drm_bridge *bridge;
> +
> + if (!new_conn_state->best_encoder)
> + continue;
> +
> + if (!new_conn_state->crtc->state->active ||
> + !drm_atomic_crtc_needs_modeset(new_conn_state->crtc->state))
> + continue;
> +
> + encoder = new_conn_state->best_encoder;
> + /*
> + * Each encoder has at most one connector (since we always steal
> + * it away), so we won't call enable hooks twice.
> + */
> + bridge = drm_bridge_chain_get_first_bridge(encoder);
> +
> + switch (op_type) {
> + case DRM_BRIDGE_PRE_ENABLE_OR_POST_DISABLE:
> + drm_atomic_bridge_chain_pre_enable(bridge, old_state);
> + break;
> +
> + case DRM_BRIDGE_ENABLE_OR_DISABLE:
> + funcs = encoder->helper_private;
> +
> + drm_dbg_atomic(dev, "enabling [ENCODER:%d:%s]\n",
> + encoder->base.id, encoder->name);
> +
> + if (funcs) {
> + if (funcs->atomic_enable)
> + funcs->atomic_enable(encoder, old_state);
> + else if (funcs->enable)
> + funcs->enable(encoder);
> + else if (funcs->commit)
> + funcs->commit(encoder);
> + }
> +
> + drm_atomic_bridge_chain_enable(bridge, old_state);
> + break;
> +
> + default:
> + drm_err(dev, "Unrecognized Encoder/Bridge Operation (%d).\n", op_type);
> + break;
> + }
> + }
> +}
> +
> +static void
> +crtc_enable(struct drm_device *dev, struct drm_atomic_state *old_state)
> {
> struct drm_crtc *crtc;
> struct drm_crtc_state *old_crtc_state;
> struct drm_crtc_state *new_crtc_state;
> - struct drm_connector *connector;
> - struct drm_connector_state *new_conn_state;
> int i;
>
> for_each_oldnew_crtc_in_state(old_state, crtc, old_crtc_state, new_crtc_state, i) {
> @@ -1490,43 +1565,30 @@ void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
> funcs->commit(crtc);
> }
> }
> -
> - for_each_new_connector_in_state(old_state, connector, new_conn_state, i) {
> - const struct drm_encoder_helper_funcs *funcs;
> - struct drm_encoder *encoder;
> - struct drm_bridge *bridge;
> -
> - if (!new_conn_state->best_encoder)
> - continue;
> -
> - if (!new_conn_state->crtc->state->active ||
> - !drm_atomic_crtc_needs_modeset(new_conn_state->crtc->state))
> - continue;
> -
> - encoder = new_conn_state->best_encoder;
> - funcs = encoder->helper_private;
> -
> - drm_dbg_atomic(dev, "enabling [ENCODER:%d:%s]\n",
> - encoder->base.id, encoder->name);
> -
> - /*
> - * Each encoder has at most one connector (since we always steal
> - * it away), so we won't call enable hooks twice.
> - */
> - bridge = drm_bridge_chain_get_first_bridge(encoder);
> - drm_atomic_bridge_chain_pre_enable(bridge, old_state);
> -
> - if (funcs) {
> - if (funcs->atomic_enable)
> - funcs->atomic_enable(encoder, old_state);
> - else if (funcs->enable)
> - funcs->enable(encoder);
> - else if (funcs->commit)
> - funcs->commit(encoder);
> - }
> -
> - drm_atomic_bridge_chain_enable(bridge, old_state);
> - }
> +}
> +
> +/**
> + * drm_atomic_helper_commit_modeset_enables - modeset commit to enable outputs
> + * @dev: DRM device
> + * @old_state: atomic state object with old state structures
> + *
> + * This function enables all the outputs with the new configuration which had to
> + * be turned off for the update.
> + *
> + * For compatibility with legacy CRTC helpers this should be called after
> + * drm_atomic_helper_commit_planes(), which is what the default commit function
> + * does. But drivers with different needs can group the modeset commits together
> + * and do the plane commits at the end. This is useful for drivers doing runtime
> + * PM since planes updates then only happen when the CRTC is actually enabled.
> + */
> +void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
> + struct drm_atomic_state *old_state)
> +{
> + encoder_bridge_chain_enable(dev, old_state, DRM_BRIDGE_PRE_ENABLE_OR_POST_DISABLE);
> +
> + crtc_enable(dev, old_state);
> +
> + encoder_bridge_chain_enable(dev, old_state, DRM_BRIDGE_ENABLE_OR_DISABLE);
>
> drm_atomic_helper_commit_writebacks(dev, old_state);
> }
> --
> 2.34.1
>
--
With best wishes
Dmitry
