On Tue, Mar 03, 2020 at 02:57:45PM +0000, Peter Rosin wrote: > > On 2020-03-03 15:20, Thierry Reding wrote: > > On Mon, Mar 02, 2020 at 10:53:56PM +0000, Peter Rosin wrote: > >> On 2020-03-02 21:34, Ville Syrjala wrote: > >>> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > >>> > >>> The currently listed dotclock disagrees with the currently > >>> listed vrefresh rate. Change the dotclock to match the vrefresh. > >>> > >>> Someone tell me which (if either) of the dotclock or vreresh is > >>> correct? > >> > >> TL/DR; I do not care if you change the refresh rate or the dotclock. > >> > >> The whole entry for that panel in simple-panel is dubious. The panel > >> is really an LVDS panel (capable of both VESA/Jeida RGB888, selectable > >> with the SELLVDS pin). With Jeida you can, as usual, omit the 4th > >> data channel and use the panel with RGB666. In either case, you need > >> an LVDS signal and nothing else... > >> > >> The panel can also rotate the picture 180 degrees using the RL/UD pin. > >> > >> These options are of course not expressed in the simple panel driver > >> (and we have always used fixed signals for those pins in our designs, > >> IIRC). As far as I'm concerned, the panel can be removed from > >> simple-panel. Our device trees are nowadays correctly expressing the > >> hardware with an LVDS encoder between the RGB output and the panel > >> and points to the panel-lvds driver for the panel. > > > > How do you make sure that you always bind against the correct driver? If > > it matches simple-panel and panel-lvds, it's not deterministically going > > to pick the right one. Well, it may actually be deterministic on Linux, > > but perhaps only by accident. > > You are probably right that it's fragile, but no problems so far. That > said, I did wonder why the panel-lvds driver "wins" over simple-panel for > > compatible = "sharp,lq150x1lg11", "panel-lvds"; > > I figured it was by design and didn't spend too much time thinking about > it. Maybe I should have? It's most likely because panel-lvds.o is linked into the kernel before panel-simple.o and the first match wins. You may want to move the entry to panel-lvds to make this a little more robust. Thierry
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