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drm/edid: Round to closest when computing the CEA/HDMI alternate clock 

Rounding to the closest kHz seems like the better option that round
down or up when computing the alternate clock for CEA/HDMI modes.
It'll give us a slightly more accurate clock in some cases.

Not sure why I went for the down+up approach originally. Perhaps
I was thinking we can go back and forth betwen the two frequencies
without introducing errors, but round to closest still maintains
that property.

Cc: Adam Jackson <ajax@redhat.com>
Cc: Clint Taylor <clinton.a.taylor@intel.com>
Cc: Libin Yang <libin.yang@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Ville Syrjälä 2015-10-08 11:43:33 +03:00 committed by Daniel Vetter
parent fa3a7340ea
commit 9afd808cf3
1 changed files with 2 additions and 2 deletions
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4
drivers/gpu/drm/drm_edid.c
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@ -2538,9 +2538,9 @@ cea_mode_alternate_clock(const struct drm_display_mode *cea_mode)
* and the 60Hz variant otherwise.
*/
if (cea_mode->vdisplay == 240 || cea_mode->vdisplay == 480)
clock = clock * 1001 / 1000;
clock = DIV_ROUND_CLOSEST(clock * 1001, 1000);
else
clock = DIV_ROUND_UP(clock * 1000, 1001);
clock = DIV_ROUND_CLOSEST(clock * 1000, 1001);
return clock;
}