On 10/06/2016 12:51 PM, Maxime Ripard wrote: > Hi Archit, > > On Mon, Oct 03, 2016 at 04:40:57PM +0530, Archit Taneja wrote: >> Hi Maxime, >> >> On 09/30/2016 08:07 PM, Maxime Ripard wrote: >>> Some boards have an entirely passive RGB to VGA bridge, based on either >>> DACs or resistor ladders. >>> >>> Those might or might not have an i2c bus routed to the VGA connector in >>> order to access the screen EDIDs. >>> >>> Add a bridge that doesn't do anything but expose the modes available on the >>> screen, either based on the EDIDs if available, or based on the XGA >>> standards. >>> >>> Acked-by: Rob Herring <robh at kernel.org> >>> Signed-off-by: Maxime Ripard <maxime.ripard at free-electrons.com> >>> --- >>> .../bindings/display/bridge/rgb-to-vga-bridge.txt | 48 +++++ >>> drivers/gpu/drm/bridge/Kconfig | 7 + >>> drivers/gpu/drm/bridge/Makefile | 1 + >>> drivers/gpu/drm/bridge/rgb-to-vga.c | 229 >>> +++++++++++++++++++++ >>> 4 files changed, 285 insertions(+) >>> create mode 100644 >>> Documentation/devicetree/bindings/display/bridge/rgb-to-vga-bridge.txt >>> create mode 100644 drivers/gpu/drm/bridge/rgb-to-vga.c >>> >>> diff --git >>> a/Documentation/devicetree/bindings/display/bridge/rgb-to-vga-bridge.txt >>> b/Documentation/devicetree/bindings/display/bridge/rgb-to-vga-bridge.txt >>> new file mode 100644 >>> index 000000000000..a8375bc1f9cb >>> --- /dev/null >>> +++ b/Documentation/devicetree/bindings/display/bridge/rgb-to-vga-bridge.txt >>> @@ -0,0 +1,48 @@ >>> +Dumb RGB to VGA bridge >>> +---------------------- >>> + >>> +This binding is aimed for dumb RGB to VGA bridges that do not require >>> +any configuration. >>> + >>> +Required properties: >>> + >>> +- compatible: Must be "rgb-to-vga-bridge" >> >> I'd talked to Laurent on IRC if he's okay with this. And I guess you to >> had discussed it during XDC too. He's suggested that it'd be better to >> have the compatible string as "simple-vga-dac". > > I just wished this bikeshedding had taken place publicly and be > actually part of that discussion, but yeah, ok.
Sorry about that. I'd pinged him for an Ack, the discussion went more than that :) > >> Some of the reasons behind having this: >> >> - We don't need to specify "rgb" in the compatible string since most >> simple VGA DACs can only work with an RGB input. > > Ok. > >> - Also, with "dac" specified in the string, we don't need to >> specifically mention "bridge" in the string. Also, bridge is a drm >> specific term. >> >> - "simple" is considered because it's an unconfigurable bridge, and it >> might be misleading for other VGA DACs to not use "vga-dac". > > All those "simple" bindings are just the biggest lie we ever > told. It's simple when you introduce it, and then grows into something > much more complicated than a non-simple implementation. "simple" here is supposed to mean that it's an unconfigurable RGB to VGA DAC. This isn't supposed to follow the simple-panel model, where you add the "simple-panel" string in the compatible node, along with you chip specific compatible string. In other words, this driver shouldn't be touched again in the future :) If someone wants to write a RGB to VGA driver which is even slightly configurable, they'll need to write a new bridge driver. Thanks, Archit > >> What do you think about this? If you think it's good, would it be >> possible for you to change this? I guess it's okay for the rest of >> the patch to stay the same. > > I'll update and respin the serie. > > Thanks, > Maxime > -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
