On Tue, Dec 02, 2025 at 10:58:50AM +0200, Tomi Valkeinen wrote: > On 02/12/2025 08:34, Laurent Pinchart wrote: > > On Sun, Nov 30, 2025 at 01:11:16PM +0100, Linus Walleij wrote: > >> This fixes two regressions experienced in the MCDE and > >> R-Car DU DRM drivers after > >> 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. > >> > >> This series make it possible to selectively bring back the > >> old behaviour with explicit semantics and implements > >> the old behaviour as modified commit tails in MCDE and > >> R-Car DU. > > > > We now have a third platform broken by > > c9b1150a68d9362a0827609fc0dc1664c0d8bfe1, see [1]. I think this calls > > for a revert, to give us the time to implement a correct solution. > > Perhaps... It's been very slow or not possible to get feedback regarding > (some) of the broken platforms, so I don't think we have a safe way of > changing the enable/disable sequence. I think the "correct" solution > then is to make this new enable/disable sequence either opt-in, offered > by the framework, or just implement it as a custom sequence in the > specific drm driver.
I don't think that's right, sorry. We need to improve the bridge API to handle ordering properly. Changes to the commit tail handlers in display controller drivers are hacks, they handle issues with the internal DSI transmitters, but if you had a LVDS-to-DSI bridge in the pipeline things would still break. > Reverting c9b1150a68d9362a0827609fc0dc1664c0d8bfe1 will break DSI and > OLDI outputs on TI platforms, so we need to implement a fix for those > platforms before the revert, and there has been one or two fixes merged > for other platforms for this, which most likely also need to get reverted. That's 3 vs. 1, so I think breaking DSI and OLDI with a revert is better than not reverting the commit. If we can merge a propert solution at the same time that's great, but the first target is to restore operation of the drivers that got broken. > > [1] > > https://lore.kernel.org/r/caamcf8di8sc_xvzanzq9suiuf-ayvg2yjhx2dwmvvcnff3p...@mail.gmail.com > > > >> Signed-off-by: Linus Walleij <[email protected]> > >> --- > >> Changes in v5: > >> - Prefix all exported atomic commit helpers with drm_atomic_helper_commit_* > >> - Add kerneldoc to all new exported atmomic commit helpers. > >> - Add comments into the MCDE and Rcar DU quirks explaining what is > >> altered as compared to the standard helper functions. > >> - Link to v4: > >> https://lore.kernel.org/r/20251121-mcde-drm-regression-thirdfix-v4-0-d89bf8c17...@linaro.org > >> > >> Changes in v4: > >> - Fix a copypaste-bug in the Renesas Rcar-DU driver. > >> - Actually compile this using the shmobile defconfig and make > >> sure it works. > >> - Collect Geert's Tested-by. > >> - Link to v3: > >> https://lore.kernel.org/r/20251120-mcde-drm-regression-thirdfix-v3-0-24b1e9886...@linaro.org > >> > >> Changes in v3: > >> - Switch to a new approach: export helper functions and create the > >> special helper directly in the driver instead. > >> - Drop Marek's patch and write a new RFT patch with the same > >> semantic content as the MCDE patch. > >> - Link to v2: > >> https://lore.kernel.org/r/[email protected] > >> > >> Changes in v2: > >> - Queue Marek's patch first in the series for coherency. > >> - Add a patch to also preserve the late CRTC disablement > >> semantic. > >> - Rename helper function to reflect the new semantic. > >> - Update the MCDE patch to use the new callbacks. > >> - Link to v1: > >> https://lore.kernel.org/r/[email protected] > >> > >> --- > >> Linus Walleij (3): > >> drm/atomic-helper: Export and namespace some functions > >> drm/mcde: Create custom commit tail > >> drm/rcar-du: Modify custom commit tail > >> > >> drivers/gpu/drm/drm_atomic_helper.c | 122 > >> +++++++++++++++++++++----- > >> drivers/gpu/drm/mcde/mcde_drv.c | 45 +++++++++- > >> drivers/gpu/drm/renesas/rcar-du/rcar_du_kms.c | 33 ++++++- > >> include/drm/drm_atomic_helper.h | 22 +++++ > >> 4 files changed, 195 insertions(+), 27 deletions(-) > >> --- > >> base-commit: 6548d364a3e850326831799d7e3ea2d7bb97ba08 > >> change-id: 20251120-mcde-drm-regression-thirdfix-1b0abfb52209 -- Regards, Laurent Pinchart
