Re: drm/bridge: dw_hdmi: Colorspace registers

[Jose Abreu <Jose.Abreu@synopsys.com>]

Hi Russell,


On 17-08-2016 12:21, Russell King - ARM Linux wrote:
> On Wed, Aug 17, 2016 at 10:33:10AM +0100, Jose Abreu wrote:
>> Hi Russell,
>>
>> When using driver dw-hdmi in any other colorspace than RGB the
>> Y1, Y0 and YCC values are not correct. I confirmed in databook
>> that these registers are being written to the wrong offset (per
>> my databook they should be written in bits 0:1 and 7 instead of
>> bits 4:5). The piece of code in question is this:
>>
>>     val = (frame.colorspace & 3) << 4 | (frame.scan_mode & 0x3);
>>
>> So colorspace is being written to bits 4 and 5 instead of bits 0,
>> 1 and 7.
> You're half-right.  The above should be:
>
> 	val = (frame.colorspace & 3) | (frame.scan_mode & 3) << 4;
>
> I'm not sure why you're saying about bit 7 - this is labelled in the
> iMX6 manuals as "FC_AVICONF0_MISC" and "Frame composer AVI packet
> configuration bit" which is not a very useful description.  So I'm
> not sure that bit 7 is part of the colorspace configuration.

This is bit Y2 of rgb_ycc_indication but I am reading CEA-861-F
and this bit is reserved so it shouldn't matter. I will send a
patch to correct this.

>
> Unfortunately, all I have to go on is what's reproduced in the iMX6
> TRMs as I have no access to the Synopsis databooks.
>

Best regards,
Jose Miguel Abreu
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