leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

drm/radeon: avoid high jitter with small frac divs

Browse Source 
Signed-off-by: Christian König <christian.koenig@amd.com>
This commit is contained in:
Christian König 2014-04-24 18:39:59 +02:00
parent 695daf1a8e
commit 3b333c5548
1 changed files with 12 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/gpu/drm/radeon/radeon_display.c
View File

@ -830,14 +830,14 @@ static void avivo_reduce_ratio(unsigned *nom, unsigned *den,
/* make sure nominator is large enough */
if (*nom < nom_min) {
tmp = (nom_min + *nom - 1) / *nom;
tmp = DIV_ROUND_UP(nom_min, *nom);
*nom *= tmp;
*den *= tmp;
}
/* make sure the denominator is large enough */
if (*den < den_min) {
tmp = (den_min + *den - 1) / *den;
tmp = DIV_ROUND_UP(den_min, *den);
*nom *= tmp;
*den *= tmp;
}
@ -997,6 +997,16 @@ void radeon_compute_pll_avivo(struct radeon_pll *pll,
/* this also makes sure that the reference divider is large enough */
avivo_reduce_ratio(&fb_div, &ref_div, fb_div_min, ref_div_min);
/* avoid high jitter with small fractional dividers */
if (pll->flags & RADEON_PLL_USE_FRAC_FB_DIV && (fb_div % 10)) {
fb_div_min = max(fb_div_min, (9 - (fb_div % 10)) * 20 + 60);
if (fb_div < fb_div_min) {
unsigned tmp = DIV_ROUND_UP(fb_div_min, fb_div);
fb_div *= tmp;
ref_div *= tmp;
}
}
/* and finally save the result */
if (pll->flags & RADEON_PLL_USE_FRAC_FB_DIV) {
*fb_div_p = fb_div / 10;