Rob, On Fri, Jun 10, 2016 at 11:43 AM, Rob Clark <robdclark@xxxxxxxxx> wrote: > On Fri, Jun 10, 2016 at 1:02 PM, Douglas Anderson <dianders@xxxxxxxxxxxx> wrote: >> The Starry KR122EA0SRA is a 12.2", 1920x1200 TFT-LCD panel connected >> using eDP interfaces. > > so drive-by comment... but shouldn't eDP be probe-able? Not sure why > we need panel drivers or DT bindings? I was wondering about that too. As far as I can tell: 1. We need a panel driver because that appears to be what owns a reference to the backlight / panel power regulator and that part is not auto-probable. 2. As far as I could tell, there is no way to declare a generic (unspecified) panel in the device tree. Everyone seems to include "simple-panel" in their compatible string but as far as I can tell nothing in the kernel looks at it. 3. In theory, all the info specified here should match the EDID exactly and thus (as you said) be probable. However, it sounds like (for power sequencing reasons) there might be reasons why you'd want to know exactly what panel was present beforehand. You might need to power the panel and backlight in very specific sequences, for instance. I'm not sure it's always 100% possible in all embedded designs to read the EDID before you know how the sequencing should work (but, of course, I'm a NOOB). 4. Reading the EDID can be slow. If you happen to know all the info on the panel beforehand you can significantly speed up boot speed, notably how fast you can get something on the screen. Anyway, maybe someone else who actually knows what they're talking about will chime in. ;) -Doug -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
