This adds (yet another) variant of the drm_atomic_helper_commit_tail() helper function to deal with regressions caused by reordering the bridge prepare/enablement sequence.
commit c9b1150a68d9362a0827609fc0dc1664c0d8bfe1 "drm/atomic-helper: Re-order bridge chain pre-enable and post-disable" caused a series of regressions in all panels that send DSI commands in their .prepare() and .unprepare() callbacks. As the CRTC is no longer online at bridge_pre_enable() and gone at brige_post_disable() which maps to the panel bridge .prepare()/.unprepare() callbacks, any CRTC that enable/disable the DSI transmitter in it's enable/disable callbacks will be unable to send any DSI commands in the .prepare() and .unprepare() callbacks. However the MCDE driver definitely need the CRTC to be enabled during .prepare()/.unprepare(). This patch from Marek Vasut: https://lore.kernel.org/all/20251107230517.471894-1-marek.vasut%2Brenesas%40mailbox.org/ solves part of the problem for drivers using custom tail functions, since MCDE is using helpers only, we add a new helper function that exploits the new drm_atomic_helper_commit_modeset_enables_crtc_early() and use that in MCDE. Link: https://lore.kernel.org/dri-devel/[email protected]/ Link: https://lore.kernel.org/all/20251107230517.471894-1-marek.vasut%2Brenesas%40mailbox.org/ Fixes: c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable") Signed-off-by: Linus Walleij <[email protected]> --- This obviously needs Marek's patch to be applied first, as it is a prerequisite. --- drivers/gpu/drm/drm_atomic_helper.c | 32 ++++++++++++++++++++++++++++++++ drivers/gpu/drm/mcde/mcde_drv.c | 5 +++-- include/drm/drm_atomic_helper.h | 1 + 3 files changed, 36 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index f03b93c72b8f..fe30159d13b1 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1976,6 +1976,38 @@ void drm_atomic_helper_commit_tail_rpm(struct drm_atomic_state *state) } EXPORT_SYMBOL(drm_atomic_helper_commit_tail_rpm); +/** + * drm_atomic_helper_commit_tail_early - commit atomic update to hardware + * @state: new modeset state to be committed + * + * This is an alternative implementation for the + * &drm_mode_config_helper_funcs.atomic_commit_tail hook, for drivers + * that support runtime_pm or need the CRTC to be enabled to perform a + * commit, and also need the CRTC to be enabled before preparing any + * bridhes. Otherwise, one should use the default implementation + * drm_atomic_helper_commit_tail(). + */ +void drm_atomic_helper_commit_tail_early(struct drm_atomic_state *state) +{ + struct drm_device *dev = state->dev; + + drm_atomic_helper_commit_modeset_disables(dev, state); + + drm_atomic_helper_commit_modeset_enables_crtc_early(dev, state); + + drm_atomic_helper_commit_planes(dev, state, + DRM_PLANE_COMMIT_ACTIVE_ONLY); + + drm_atomic_helper_fake_vblank(state); + + drm_atomic_helper_commit_hw_done(state); + + drm_atomic_helper_wait_for_vblanks(dev, state); + + drm_atomic_helper_cleanup_planes(dev, state); +} +EXPORT_SYMBOL(drm_atomic_helper_commit_tail_early); + static void commit_tail(struct drm_atomic_state *state) { struct drm_device *dev = state->dev; diff --git a/drivers/gpu/drm/mcde/mcde_drv.c b/drivers/gpu/drm/mcde/mcde_drv.c index 5f2c462bad7e..4d88b342ed9e 100644 --- a/drivers/gpu/drm/mcde/mcde_drv.c +++ b/drivers/gpu/drm/mcde/mcde_drv.c @@ -104,9 +104,10 @@ static const struct drm_mode_config_helper_funcs mcde_mode_config_helpers = { /* * Using this function is necessary to commit atomic updates * that need the CRTC to be enabled before a commit, as is - * the case with e.g. DSI displays. + * the case with e.g. DSI displays, and also make sure that the + * CRTC is enabled before any bridges are prepared. */ - .atomic_commit_tail = drm_atomic_helper_commit_tail_rpm, + .atomic_commit_tail = drm_atomic_helper_commit_tail_early, }; static irqreturn_t mcde_irq(int irq, void *data) diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h index d7fb473db343..75e480760313 100644 --- a/include/drm/drm_atomic_helper.h +++ b/include/drm/drm_atomic_helper.h @@ -64,6 +64,7 @@ int drm_atomic_helper_check(struct drm_device *dev, struct drm_atomic_state *state); void drm_atomic_helper_commit_tail(struct drm_atomic_state *state); void drm_atomic_helper_commit_tail_rpm(struct drm_atomic_state *state); +void drm_atomic_helper_commit_tail_early(struct drm_atomic_state *state); int drm_atomic_helper_commit(struct drm_device *dev, struct drm_atomic_state *state, bool nonblock); --- base-commit: 643e6ae9e34fc3a87c7953b6929265e93b9c38e1 change-id: 20251118-mcde-drm-regression-33deb78a968f Best regards, -- Linus Walleij <[email protected]>
