Messages in this thread | | | Subject | Re: [PATCH 3/8] drm/vc4: Use drm_mode_vrefresh() in DSI fixup, in case vrefresh is 0. | From | Andrzej Hajda <> | Date | Thu, 29 Jun 2017 11:24:49 +0200 |
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On 27.06.2017 21:58, Eric Anholt wrote: > I'm not sure what changed where I started getting vrefresh=0 from the > mode to be fixed up.
It can be a case of low pixel_clock value, maybe it should be investigated further, unless there is execution path with forgotten mode->vrefresh =
drm_mode_vrefresh(mode)
> > Signed-off-by: Eric Anholt <eric@anholt.net> > --- > drivers/gpu/drm/vc4/vc4_dsi.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c > index 629d372633e6..fca4d7fd677e 100644 > --- a/drivers/gpu/drm/vc4/vc4_dsi.c > +++ b/drivers/gpu/drm/vc4/vc4_dsi.c > @@ -866,7 +866,9 @@ 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 = pixel_clock_hz / (drm_mode_vrefresh(mode) * > + mode->vtotal); > +
I am not sure but I guess division by zero is also possible here. I do not know if you need to handle interlaced/dblscan/vscan modes, but maybe it would be safer to calculate adjusted_htotal according to:
adjusted_mode->htotal = pixel_clock_hz * mode->htotal / (mode->clock * 1000)
or sth similar.
Regards Andrzej
> adjusted_mode->hsync_end += adjusted_mode->htotal - mode->htotal; > adjusted_mode->hsync_start += adjusted_mode->htotal - mode->htotal; >
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