Re: [PATCH v2 14/20] drm/sun4i: tcon: multiply the vtotal when not in interlace

From	icenowy@aosc.io
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 14/20] drm/sun4i: tcon: multiply the vtotal when not in interlace
Date	2017-05-05 10:20 +0200
Message-ID	<tDGCZ-7zW-3@gated-at.bofh.it> (permalink)
References	<tD1gu-5a8-5@gated-at.bofh.it> <tD1gu-5a8-7@gated-at.bofh.it>
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在 2017-05-03 19:59，Maxime Ripard 写道：
> It appears that the total vertical resolution needs to be doubled when
> we're not in interlaced. Make sure that is the case.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> ---
>  drivers/gpu/drm/sun4i/sun4i_tcon.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index 0f91ec8a4b26..efa079c1a3f5 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -272,9 +272,9 @@ void sun4i_tcon1_mode_set(struct sun4i_tcon *tcon,
>  	/* Set vertical display timings */
>  	bp = mode->crtc_vtotal - mode->crtc_vsync_start;
>  	DRM_DEBUG_DRIVER("Setting vertical total %d, backporch %d\n",
> -			 mode->vtotal, bp);
> +			 mode->crtc_vtotal, bp);
>  	regmap_write(tcon->regs, SUN4I_TCON1_BASIC4_REG,
> -		     SUN4I_TCON1_BASIC4_V_TOTAL(mode->vtotal) |
> +		     SUN4I_TCON1_BASIC4_V_TOTAL(mode->crtc_vtotal * 2) |

For TVE the value should directly be mode->vtotal, but not
mode->crtc_vtotal * 2.

vtotal is 625 when PAL. crtc_vtotal is thus 312, but if we restore the
vtotal value by doubling crtv_vtotal, we got 624, which will lead to
instability of the image displayed. (the image will loop to go higher
and then go lower, because wrong vtotal value)

Tested on patched H3 TV encoder.

I used a logic slightly changed from your v1 code:

```
	val = mode->vtotal;
	if (!(mode->flags & DRM_MODE_FLAG_INTERLACE))
		val = val * 2;
	regmap_write(tcon->regs, SUN4I_TCON1_BASIC4_REG,
		     SUN4I_TCON1_BASIC4_V_TOTAL(val) |
		     SUN4I_TCON1_BASIC4_V_BACKPORCH(bp));
```

>  		     SUN4I_TCON1_BASIC4_V_BACKPORCH(bp));
> 
>  	/* Set Hsync and Vsync length */

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[PATCH v2 14/20] drm/sun4i: tcon: multiply the vtotal when not in interlace Maxime Ripard <maxime.ripard@free-electrons.com> - 2017-05-03 14:10 +0200
  Re: [PATCH v2 14/20] drm/sun4i: tcon: multiply the vtotal when not in interlace Chen-Yu Tsai <wens@csie.org> - 2017-05-04 06:10 +0200
  Re: [PATCH v2 14/20] drm/sun4i: tcon: multiply the vtotal when not in  interlace icenowy@aosc.io - 2017-05-05 10:20 +0200

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