On 2020-03-03 16:05, Thierry Reding wrote:
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@linux.intel.com
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.
Ok, or because I dropped the simple-panel driver when we no longer depended on it. Either way, what do you mean "move to [..] panel-lvds"? It has no list of panels, you have to end with "panel-lvds" in the compatible for the driver to bind.
Cheers, Peter