On Thu, Mar 16, 2023 at 11:29:53PM +0100, Michael Riesch wrote: > Hi Rob, > > On 3/16/23 22:57, Rob Herring wrote: > > On Tue, Mar 14, 2023 at 12:56:44PM +0100, Gerald Loacker wrote: > >> The sitronix-st7789v driver now considers the panel-timing property. > > > > I read the patch for that and still don't know 'why'. Commit messages > > should answer why. > > > >> Add the property to the documentation. > > > > We generally don't put timings in DT for panels. Why is this one > > special? > > For now, having the timings in the device tree allows for setting the > hsync/vsync/de polarity. > > As a next step, we aim to implement the partial mode feature of this > panel. It is possible to use only a certain region of the panel, which > is helpful e.g., when a part of the panel is occluded and should not be > considered by DRM. We thought that this could be specified as timing in DT. > > (The hactive and vactive properties serve as dimensions of this certain > region, of course. We still need to specify somehow the position of the > region. Maybe with additional properties hactive-start and vactive-start?) > > What do you think about that? I don't see why we would need the device tree to support that. What you described is essentially what overscan is for HDMI/analog output, and we already have everything to deal with overscan properly in KMS. Maxime
