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Commit 84c82ab8 authored by Christian König's avatar Christian König Committed by Greg Kroah-Hartman
Browse files

drm/radeon: prefer lower reference dividers 

commit 2e26ccb119bde03584be53406bbd22e711b0d6e6 upstream.

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: default avatarPaul Dufresne <dufresnep@gmail.com>
Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Acked-by: default avatarAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 748a97ec

drivers/gpu/drm/radeon/radeon_display.c

+2 −2
Original line number Diff line number Diff line
@@ -921,12 +921,12 @@ 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;

	}

}