diff options
| author |   Eric Anholt <eric@anholt.net> | 2017-08-15 16:47:19 -0700 |
|---|---|---|
| committer | Eric Anholt <eric@anholt.net> | 2017-09-27 11:54:35 -0700 |
| commit | af2eca53206c59ce9308a4f5f46c4a104a179b6b (patch) | |
| tree | 521b1f7d3171df1aa0ad4b77f2b1067fe96efa53 /drivers/gpu/drm/vc4 | |
| parent | drm/Documentation: Refine TODO for backlight helpers in tinydrm (diff) | |
| download | linux-dev-af2eca53206c59ce9308a4f5f46c4a104a179b6b.tar.xz linux-dev-af2eca53206c59ce9308a4f5f46c4a104a179b6b.zip | |
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>
Diffstat (limited to 'drivers/gpu/drm/vc4')
| -rw-r--r-- | drivers/gpu/drm/vc4/vc4_dsi.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c index d1e0dc908048..04796d7d0fdb 100644 --- a/drivers/gpu/drm/vc4/vc4_dsi.c +++ b/drivers/gpu/drm/vc4/vc4_dsi.c @@ -866,7 +866,8 @@ static bool vc4_dsi_encoder_mode_fixup(struct drm_encoder *encoder, adjusted_mode->clock = pixel_clock_hz / 1000 + 1; /* Given the new pixel clock, adjust HFP to keep vrefresh the same. */ - adjusted_mode->htotal = pixel_clock_hz / (mode->vrefresh * mode->vtotal); + adjusted_mode->htotal = adjusted_mode->clock * mode->htotal / + mode->clock; adjusted_mode->hsync_end += adjusted_mode->htotal - mode->htotal; adjusted_mode->hsync_start += adjusted_mode->htotal - mode->htotal; |