On Thu, Mar 06, 2025 at 03:02:41PM +0800, Liu Ying wrote: > On 03/06/2025, Rob Herring wrote: > > On Wed, Mar 05, 2025 at 10:35:26AM +0100, Alexander Stein wrote: > >> Hi, > >> > >> Am Dienstag, 4. März 2025, 16:23:20 CET schrieb Rob Herring: > >>> On Tue, Mar 04, 2025 at 06:15:28PM +0800, Liu Ying wrote: > >>>> A DPI color encoder, as a simple display bridge, converts input DPI color > >>>> coding to output DPI color coding, like Adafruit Kippah DPI hat[1] which > >>>> converts input 18-bit pixel data to 24-bit pixel data(with 2 low padding > >>>> bits in every color component though). Document the DPI color encoder. > >>> > >>> Why do we need a node for this? Isn't this just wired how it is wired > >>> and there's nothing for s/w to see or do? I suppose if you are trying to > >>> resolve the mode with 24-bit on one end and 18-bit on the other end, you > >>> need to allow that and not require an exact match. You still might need > >>> to figure out which pins the 18-bit data comes out on, but you have that > >>> problem with an 18-bit panel too. IOW, how is this any different if you > >>> have an 18-bit panel versus 24-bit panel? > >> > >> Especially panel-simple.c has a fixed configuration for each display, such as: > >>> .bus_format = MEDIA_BUS_FMT_RGB666_1X18 > >> > >> How would you allow or even know it should be addressed as > >> MEDIA_BUS_FMT_RGB888_1X24 instead? I see different ways: > >> 1. Create a new display setting/compatible > >> 2. Add an overwrite property to the displays > >> 3. Use a (transparent) bridge (this series) > >> > >> Number 1 is IMHO out of question. > > > > Agreed. > > > >> I personally don't like number 2 as this > >> feels like adding quirks to displays, which they don't have. > > > > This is what I would do except apply it to the controller side. We know > > the panel side already. This is a board variation, so a property makes > > sense. I don't think you need any more than knowing what's on each end. > > With option 2, no matter putting a property in source side or sink side, > impacted display drivers and DT bindings need to be changed, once a board > manipulates the DPI color coding. This adds burdens and introduces new > versions of those DT bindings. Is this what we want? There's an option 4: make it a property of the OF graph endpoints. In essence, it's similar to properties that are already there like lane-mapping, and it wouldn't affect the panel drivers, or create an intermediate bridge. Maxime
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