drm/vc4: Avoid using vrefresh==0 mode in DSI htotal math.
authorEric Anholt <eric@anholt.net>
Tue, 15 Aug 2017 23:47:19 +0000 (16:47 -0700)
committerEric Anholt <eric@anholt.net>
Wed, 27 Sep 2017 18:54:35 +0000 (11:54 -0700)
commitaf2eca53206c59ce9308a4f5f46c4a104a179b6b
tree521b1f7d3171df1aa0ad4b77f2b1067fe96efa53
parent9949b355dc1c259b4ed3c092b899b7e9cf166236
drm/vc4: Avoid using vrefresh==0 mode in DSI htotal math.

The incoming mode might have a missing vrefresh field if it came from
drmModeSetCrtc(), which the kernel is supposed to calculate using
drm_mode_vrefresh().  We could either use that or the adjusted_mode's
original vrefresh value.

However, we can maintain a more exact vrefresh value (not just the
integer approximation), by scaling by the ratio of our clocks.

v2: Use math suggested by Andrzej Hajda instead.
v3: Simplify math now that adjusted_mode->clock isn't padded.
v4: Drop some parens.

Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20170815234722.20700-2-eric@anholt.net
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
drivers/gpu/drm/vc4/vc4_dsi.c