Hi Archit, On Friday 22 Apr 2016 11:10:18 Archit Taneja wrote: > On 04/22/2016 04:02 AM, Laurent Pinchart wrote: > > On Wednesday 09 Mar 2016 16:27:18 Archit Taneja wrote: > >> Add description of ADV7533. Add the required and optional properties that > >> are specific to it. > >> > >> Cc: devicetree@xxxxxxxxxxxxxxx > >> Cc: Rob Herring <robh@xxxxxxxxxx> > >> > >> Signed-off-by: Archit Taneja <architt@xxxxxxxxxxxxxx> > >> --- > >> > >> .../bindings/display/bridge/adi,adv7511.txt | 25 ++++++++++++----- > >> 1 file changed, 20 insertions(+), 5 deletions(-) > >> > >> diff --git > >> a/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt > >> b/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt index > >> 96c25ee..420da5a 100644 > >> --- a/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt > >> +++ b/Documentation/devicetree/bindings/display/bridge/adi,adv7511.txt [snip] > >> +- adi,disable-timing-generator: Only for ADV7533. Disables the internal > >> timing > >> + generator. The chip will rely on the sync signals in the DSI data > >> lanes, > >> + rather than generate its own timings for HDMI output. > > > > Isn't that something that should be selectable at runtime ? > > The timing generator can be enabled/disabled at runtime. Although, we > don't have a way to tell the driver whether we want to keep it enabled > or not. > > It's a hardware feature that works well on most platforms, but not on > all. In particular, it works well on DB410c, but causes issues with > the Hikey 96 board. The DSI host on Hikey has different clock sources > that generate the display controller's pixel clock and DSI byte clock, > whereas the Qualcomm SoC uses the same source. My guess is that the > ADV7533's timing generator doesn't like it when the pixel data and > clock are out of phase or something. > > Since it is a hardware feature which needs tweaking, I thought it > qualified as a DT property. The fact that a hardware generator is present is certainly describes the hardware, but I'm not sure whether to enable it or not also qualifies as a hardware feature. Are there use cases for using the timing generator conditionally on a given board ? As you implement support for disabling it, I assume it's not mandatory. What feature(s) do we lose if we keep it disabled ? -- Regards, Laurent Pinchart -- 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
