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@vger.kernel.org Cc: Rob Herring robh@kernel.org
Signed-off-by: Archit Taneja architt@codeaurora.org
.../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 ?