Re: [PATCH 12/15] drm/sun4i: tcon: multiply the vtotal when not in interlace

Maxime Ripard
2017-03-09T10:54:50Z

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On Tue, Mar 07, 2017 at 06:05:17PM +0800, Chen-Yu Tsai wrote:
> Hi,
>
> On Tue, Mar 7, 2017 at 4:56 PM, Maxime Ripard
> <maxime.ripard@free-electrons.com> wrote:
> > It appears that the total vertical resolution needs to be doubled when
> > we're not in interlaced. Make sure that is the case.
>
> This is true for both channels, though we handle them differently.
>
> >
> > Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> > ---
> > drivers/gpu/drm/sun4i/sun4i_tcon.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > index e44217fb4f6f..515fa56c1e6a 100644
> > --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> > @@ -248,10 +248,13 @@ void sun4i_tcon1_mode_set(struct sun4i_tcon *tcon, struct drm_encoder *encoder,
> > SUN4I_TCON1_BASIC3_H_BACKPORCH(bp));
> >
> > bp = mode->crtc_vtotal - mode->crtc_vsync_start;
> > + val = mode->crtc_vtotal;
> > + if (!(mode->flags & DRM_MODE_FLAG_INTERLACE))
> > + val = val * 2;
> > DRM_DEBUG_DRIVER("Setting vertical total %d, backporch %d\n",
> > mode->vtotal, bp);
> > regmap_write(tcon->regs, SUN4I_TCON1_BASIC4_REG,
> > - SUN4I_TCON1_BASIC4_V_TOTAL(mode->vtotal) |
> > + SUN4I_TCON1_BASIC4_V_TOTAL(val) |
>
> For channel 0, the SUN4I_TCON0_BASIC2_V_TOTAL macro multiplies the passed in
> value by 2. I think we should do the same for channel 1, and instead halve the
> value passed in if we are outputting interlaced data. I think this makes more
> sense because:
>
> 1) The register description for both channels are the same. Handling them
> consistently will result in less confusion, such as this one.
>
> 2) The definition of interlaced modes is a frame is separated into odd and
> even fields, with each field contains half the number of lines of the
> full frame. One field is displayed during each VSYNC cycle. The TCON does
> not know whether it's interlaced video or not. It only knows the display
> timings. In this case, the number of horizontal lines per cycle is key.

Hmm, yes, you're right. I'll fix it in the next release.

Thanks!
Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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