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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