On Thu, Mar 15, 2012 at 05:18:28PM +0530, Chandrabhanu Mahapatra wrote: > In OMAP3 and OMAP4, the DISPC Scaler can downscale an image up to 4 times, and > up to 2 times in OMAP2. However, with predecimation, the image can be reduced > to 16 times by fetching only the necessary pixels in memory. Then this > predecimated image can be downscaled further by the DISPC scaler. Now, where does that number 16 come from? IIRC the hardware can skip basically any number of pixels/rows. I certainly didn't add any such limit to the code in the harmattan kernel, and distinctly remember being able to downscale the N9/N950 UI even down to 1 pixel size :) > Based on the downscaling required, a prior calculation of predecimation values > for width and height of an image is done. Since, Predecimation reduces quality > of an image higher priorty is given to DISPC Scaler for downscaling. > > This code was successfully tested on OMAP2, OMAP3 and OMAP4. Horizontal and > vertical predecimation worked fine except for some synclost errors due to > undocumented errata in OMAP3 which are fixed later and skewed images were seen > on OMAP2 and OMAP3 during horizontal predecimation which will be addressed in > the future patches. All the rotation offset calculations still look suspiciously different to what is in the harmattan kernel. I remember that the original code was quite broken, and I fixed a lot of things when I was implementing pre-decimation and some rotation stuff for the N9/N950. Too bad I never managed to push that stuff upstream... -- Ville Syrjälä syrjala@xxxxxx http://www.sci.fi/~syrjala/ -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
