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Commit f8a2645e authored by Christian König's avatar Christian König
Browse files

drm/radeon: improve PLL params if we don't match exactly v2 



Otherwise we might be quite off on older chipsets.

v2: keep ref_div minimum

Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
parent 74073c9d

drivers/gpu/drm/radeon/radeon_display.c

+7 −6
Original line number Diff line number Diff line
@@ -865,7 +865,7 @@ void radeon_compute_pll_avivo(struct radeon_pll *pll, 
	unsigned post_div_min, post_div_max, post_div;

	unsigned ref_div_min, ref_div_max, ref_div;

	unsigned post_div_best, diff_best;

	unsigned nom, den, tmp;

	unsigned nom, den;



	/* determine allowed feedback divider range */

	fb_div_min = pll->min_feedback_div;
@@ -941,22 +941,23 @@ void radeon_compute_pll_avivo(struct radeon_pll *pll, 
	ref_div_max = min(210 / post_div, ref_div_max);



	/* get matching reference and feedback divider */

	ref_div = max(den / post_div, 1u);

	fb_div = nom;

	ref_div = max(DIV_ROUND_CLOSEST(den, post_div), 1u);

	fb_div = DIV_ROUND_CLOSEST(nom * ref_div * post_div, den);



	/* we're almost done, but reference and feedback

	   divider might be to large now */



	tmp = ref_div;

	nom = fb_div;

	den = ref_div;



        if (fb_div > fb_div_max) {

		ref_div = ref_div * fb_div_max / fb_div;

		ref_div = DIV_ROUND_CLOSEST(den * fb_div_max, nom);

		fb_div = fb_div_max;

	}



	if (ref_div > ref_div_max) {

		ref_div = ref_div_max;

		fb_div = nom * ref_div_max / tmp;

		fb_div = DIV_ROUND_CLOSEST(nom * ref_div_max, den);

	}



	/* reduce the numbers to a simpler ratio once more */