Re: [PATCH 1/2] OMAPDSS: DISPC: Update Fir Coefficients

Tomi Valkeinen
2011-12-15T08:55:37Z

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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.

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

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