drm/vc4: Avoid using vrefresh==0 mode in DSI htotal math.

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[ Upstream commit af2eca5320 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Eric Anholt 2017-08-15 16:47:19 -07:00 • committed by Greg Kroah-Hartman

parent 80879ecb46

commit 0d74c05ca7

1 changed files with 2 additions and 1 deletions

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drivers/gpu/drm/vc4/vc4_dsi.c

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