Re: downscaling YUV fails

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

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On 2012-12-19 12:51, Peter Meerwald wrote:
> Hello,
> 
>> In the case we set it to 4, the DISPC_FCLK is fast enough to do the required
>> downscaling, but in the case when it's set to 0, it might need to pre decimate
>> rather than try to scale.
> 
> this is my understanding as well
> 
>>> I think there is a bug downscaling YUV data when resorting to
>>> pre-decimation; setting CONFIG_OMAP2_DSS_MIN_FCK_PER_PCK is a workaround
>>> -- any ideas how this can be fixed?
> 
>> Pre-decimation should work for YUV formats also. Could you share DISPC reg
>> dumps when this happens:
>>
>> mount -t debugfs debugfs /sys/kernel/debug
>> cat /sys/kernel/debug/omapdss/dispc
> 
> please find the files http://pmeerw.net/ok.dispc (with FCK_PER_PCK=4) and 
> http://pmeerw.net/fail.dispc (FCK_PER_PCK=0)

Something funny is going on here. I can reproduce on omap3 with a few
hacks that reduce the clocks. The PICTURE_SIZE's width field is
different for working and non-working cases, but I think it should be
the same for both.

Even more interesting, with my tests I first setup the ovl with a test
picture, and see the issue (with RGB mode also). If I then use fbset to
first set the mode to YUV and then back to RGB, predecimation is not
used and the issue is not visible...

 Tomi



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