drm/radeon: prefer lower reference dividers

Instead of the closest reference divider prefer the lowest,
this fixes flickering issues on HP Compaq nx9420.

Bugs: https://bugs.freedesktop.org/show_bug.cgi?id=108514
Suggested-by: Paul Dufresne <dufresnep@gmail.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Christian König 2019-05-06 19:57:52 +02:00 committed by Alex Deucher
parent db8a974f7e
commit 2e26ccb119

View File

@ -922,12 +922,12 @@ static void avivo_get_fb_ref_div(unsigned nom, unsigned den, unsigned post_div,
ref_div_max = max(min(100 / post_div, ref_div_max), 1u);
/* get matching reference and feedback divider */
*ref_div = min(max(DIV_ROUND_CLOSEST(den, post_div), 1u), ref_div_max);
*ref_div = min(max(den/post_div, 1u), ref_div_max);
*fb_div = DIV_ROUND_CLOSEST(nom * *ref_div * post_div, den);
/* limit fb divider to its maximum */
if (*fb_div > fb_div_max) {
*ref_div = DIV_ROUND_CLOSEST(*ref_div * fb_div_max, *fb_div);
*ref_div = (*ref_div * fb_div_max)/(*fb_div);
*fb_div = fb_div_max;
}
}