On Thu, Dec 15, 2011 at 2:25 PM, Tomi Valkeinen <tomi.valkeinen@xxxxxx> wrote: > On Wed, 2011-12-14 at 10:21 +0530, Chandrabhanu Mahapatra wrote: > >> +const struct dispc_coef *dispc_ovl_get_scale_coef(int inc, int five_taps) >> +{ >> + int i; >> + static const struct { >> + int Mmin; >> + int Mmax; >> + const struct dispc_coef *coef_3; >> + const struct dispc_coef *coef_5; >> + } coefs[] = { >> + { 26, 32, coef3_M32, coef5_M32 }, >> + { 22, 26, coef3_M26, coef5_M26 }, >> + { 19, 22, coef3_M22, coef5_M22 }, >> + { 16, 19, coef3_M19, coef5_M19 }, >> + { 14, 16, coef3_M16, coef5_M16 }, >> + { 13, 14, coef3_M14, coef5_M14 }, >> + { 12, 13, coef3_M13, coef5_M13 }, >> + { 11, 12, coef3_M12, coef5_M12 }, >> + { 10, 11, coef3_M11, coef5_M11 }, >> + { 9, 10, coef3_M10, coef5_M10 }, >> + { 8, 9, coef3_M9, coef5_M9 }, >> + { 3, 8, coef3_M8, coef5_M8 }, >> + /* >> + * When upscaling more than two times, blockiness and outlines >> + * around the image are observed when M8 tables are used. M11, >> + * M16 and M19 tables are used to prevent this. >> + */ >> + { 2, 3, coef3_M11, coef5_M11 }, >> + { 1, 2, coef3_M16, coef5_M16 }, >> + }; >> + >> + inc /= 128; >> + for (i = 0; i < ARRAY_LEN(coefs); ++i) >> + if (inc > coefs[i].Mmin && inc <= coefs[i].Mmax) >> + return five_taps ? coefs[i].coef_5 : coefs[i].coef_3; >> + if (inc == 1) >> + return five_taps ? coef3_M19 : coef5_M19; >> + return NULL; >> +} > > Why don't you handle the inc == 1 case the same as others? Just have an > entry in the table for Mmin=0, Mmax = 1. > For inc=1 i.e. M=1 , scaling ratio is maximum as L/M=8. DISPC scaler doesnot support upscaling more than 8 itmes. Having an (Mmin,Mmax] of (0,1] will allow such cases. > Also, I think it's a bit confusing that Mmin is exclusive and Mmax is > inclusive in the comparison. It makes the table a bit hard to read, when > looking at which entry is used for which inc. I'd recommend using > inclusive comparison for both. > > Tomi > Having both inclusive will allow us to delete the extra comparison for inc==1 but in my opinion having Mmin exclusive and Mmax inclusive actually gives an clear idea of comparison. The tables mostly go by the Mmax value. For example, for inc=26 coef3/5_M26 table is selected, for inc=22 coef3/5_M22 is selected etc. If we have both Mmin and Mmax as inclusive above case becomes slightly incoherent. Say for M=26 instead of coef3/5_M26 which seems more obvious choice coef3/5_M32 is selected. For both inclusive cases to work and avoid confusion and delete extra comparison for inc==1 , I have to reverse the order of table entries in "coef" table. But for that I will have to put the "When upscaling more than two times, blockiness and outlines" comment at the beginning of the table and then start with { 1, 2, coef3_M16, coef5_M16 }. This will create even more confusion. -- Chandrabhanu Mahapatra Texas Instruments India Pvt. Ltd. -- 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