[PATCH] video: implement a dumb framebuffer driver

Stephen Warren swarren at wwwdotorg.org
Wed Apr 3 22:25:06 EDT 2013

On 04/03/2013 12:46 AM, Olof Johansson wrote:
> On Wed, Apr 03, 2013 at 12:17:10AM -0600, Stephen Warren wrote:
>> A dumb frame-buffer describes a raw memory region that may be rendered
>> to, with the assumption that the display hardware has already been set
>> up to scan out from that buffer.
>> This is useful in cases where a bootloader exists and has set up the
>> display hardware, but a Linux driver doesn't yet exist for the display
>> hardware.
>> diff --git a/Documentation/devicetree/bindings/video/dumb-framebuffer.txt b/Documentation/devicetree/bindings/video/dumb-framebuffer.txt
>> +Required properties:
>> +- format: The format of the framebuffer surface. Valid values are:
>> +  r5g6b5: A 16bpp format.
> Hm, I'm used to this being written as "rgb565", which is also the format
> string that the fsl-imx-drm binding seems to use.
> I guess actual depth can easily be derived from format.

I'd prefer the bit-widths be interleaved with the component names; doing
so is a little more precise if you end up with 2-digit component widths,
e.g. 10-bit r/g/b plus 2-bit alpha, where the multi-digit numbers would
run together otherwise and hence aren't easily algorithmically parsable.
I believe this interleaved style is more common in the graphics world
too. The IMX binding doesn't seem like a good example; the other option
besides "rgb565" is "rgb24", which could be one one many different formats.

I'll address the dumb/simple naming issue and repost.

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