On Thu Dec 11, 2025 at 10:40 AM CET, Kory Maincent wrote: > On Wed, 10 Dec 2025 19:10:45 +0100 > "Luca Ceresoli" <[email protected]> wrote: > >> Hi Köry, >> >> On Wed Nov 26, 2025 at 6:35 PM CET, Kory Maincent (TI.com) wrote: >> > The tilcdc hardware does not generate VESA-compliant sync signals. It >> > aligns the vertical sync (VS) on the second edge of the horizontal sync >> > (HS) instead of the first edge. To compensate for this hardware >> > behavior, the driver applies a timing adjustment in mode_fixup(). >> > >> > Previously, this adjustment was conditional based on the simulate_vesa_sync >> > flag, which was only set when using external encoders. This appears >> > problematic because: >> > >> > 1. The timing adjustment seems needed for the hardware behavior regardless >> > of whether an external encoder is used >> > 2. The external encoder infrastructure is driver-specific and being >> > removed due to design issues >> > 3. Boards using tilcdc without bridges (e.g., am335x-evm, am335x-evmsk) >> > may not be getting the necessary timing adjustments >> > >> > Remove the simulate_vesa_sync flag and apply the VESA sync timing >> > adjustment unconditionally, ensuring consistent behavior across all >> > configurations. While it's unclear if the previous conditional behavior >> > was causing actual issues, the unconditional adjustment better reflects >> > the hardware's characteristics. >> > >> > Signed-off-by: Kory Maincent (TI.com) <[email protected]> >> > --- >> > >> > Only few board currently use tilcdc not associated to a bridge like the >> > am335x_evm or the am335x-evmsk. >> >> Have you tested this change on any affected board? >> >> The change looks good to me but without some testing it would be risky. > > I have tested it on few boards but not these mainline devicetree as I don't > have them. > > I have tested a tilcdc with tda998x bridge (BeagleBone Black), a tilcdc with > ti,tilcdc,panel panel (BeagleBone with LCD cape), a tilcdc with it66121 bridge > (new Beagle Bone Green Eco board with HDMI cape). > That's all the boards I have.
OK, thanks for the info. For future iterations, I think it's useful to mention, for all patches that may potentially break existing hardware, such info on which hardware you have tested. Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
