[PATCH v4] of: Add videomode helper
Stephen Warren
swarren at wwwdotorg.org
Tue Sep 25 01:45:04 EST 2012
On 09/24/2012 07:42 AM, Rob Herring wrote:
> On 09/19/2012 03:20 AM, Steffen Trumtrar wrote:
>> This patch adds a helper function for parsing videomodes from the devicetree.
>> The videomode can be either converted to a struct drm_display_mode or a
>> struct fb_videomode.
>> +++ b/Documentation/devicetree/bindings/video/displaymode
>> @@ -0,0 +1,74 @@
>> +videomode bindings
>> +==================
>> +
>> +Required properties:
>> + - hactive, vactive: Display resolution
>> + - hfront-porch, hback-porch, hsync-len: Horizontal Display timing parameters
>> + in pixels
>> + vfront-porch, vback-porch, vsync-len: Vertical display timing parameters in
>> + lines
>> + - clock: displayclock in Hz
>
> A major piece missing is the LCD controller to display interface width
> and component ordering.
I thought this binding was solely defining the timing of the video
signal (hence "video mode"). Any definition of the physical interface to
the LCD/display-connector is something entirely orthogonal, so it seems
entirely reasonable to represent that separately.
>> +Example:
>> +
>> + display at 0 {
>
> It would be useful to have a compatible string here. We may not always
> know the panel type or have a fixed panel though. We could define
> "generic-lcd" or something for cases where the panel type is unknown.
>
>> + width-mm = <800>;
>> + height-mm = <480>;
I would hope that everything in the example above this point is just
that - an example, and this binding only covers the display mode
definition - i.e. that part of the example below.
If that's not the intent, as Rob says, there's a /ton/ of stuff missing.
>> + modes {
>> + mode0: mode at 0 {
>> + /* 1920x1080p24 */
>> + clock = <52000000>;
>> + hactive = <1920>;
>> + vactive = <1080>;
>> + hfront-porch = <25>;
>> + hback-porch = <25>;
>> + hsync-len = <25>;
>> + vback-porch = <2>;
>> + vfront-porch = <2>;
>> + vsync-len = <2>;
>> + hsync-active-high;
>> + };
>> + };
>> + };
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