Re: [PATCH v4 3/3] OMAPDSS: HDMI: Sysfs support to configure quantization

[Tomi Valkeinen <tomi.valkeinen@ti.com>]

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Hi,

On Wed, 2012-02-08 at 11:54 +0530, mythripk@ti.com wrote:
> From: Mythri P K <mythripk@ti.com>
> 
> Add sysfs support for the user space to configure limited range or full range
> quantization for HDMI.
> 
> Signed-off-by: Mythri P K <mythripk@ti.com>

I'd rather not add another non-standard sysfs entry.

The color range is something that desktops have to handle also, so
there's probably ways to handle it in DRM. DisplayPort also has the same
range setting, so it's not specific to HDMI.

So I propose to add a kernel API for this in the omap_dss_driver, so
that the users of omapdss may handle setting the range as they see best.

Btw, the displayport spec speaks of VESA and CEA ranges. Does HDMI spec
only speak about limited/full range?

I also only now realized that we have full/limited range setting in
video overlay's ATTRIBUTEs also. And it seems that we currently set it
always to 0, i.e. limited range. I wonder if this causes color
degradation in case the HDMI/DP output also sets limited range, and thus
the color range gets scaled down twice... 

 Tomi


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