From: David Ung <davidu@nvidia.com>
To: linux-fbdev@vger.kernel.org
Subject: RE: [PATCH] fbdev: fix CVT vertical front and back porch values
Date: Mon, 26 Jan 2015 20:21:33 +0000 [thread overview]
Message-ID: <d60f2ef79b004c0b8b5d9cc8476062a0@HQMAIL102.nvidia.com> (raw)
In-Reply-To: <1422277830-5163-1-git-send-email-tomi.valkeinen@ti.com>
> -----Original Message-----
> From: Tomi Valkeinen [mailto:tomi.valkeinen@ti.com]
> Sent: Monday, January 26, 2015 5:11 AM
> To: linux-fbdev@vger.kernel.org
> Cc: Tomi Valkeinen; David Ung; Antonino A. Daplas
> Subject: [PATCH] fbdev: fix CVT vertical front and back porch values
>
> CVT v1.1 spec says: "the vertical front porch shall in all cases be fixed to 3
> lines". The code in fbcvt.c instead sets the _back_ porch to
> 3 (plus margin).
>
> After swapping cvt.v_front_porch and cvt.v_back_porch the resulting
> timings were in line with CVT timings in VESA DMT spec.
>
> The bug seems to be more than 9 years old, but I presume it has not been
> noticed as usually the video timings come from the EDID or from the timing
> tables in fbdev, and probably swapped values for vfp and vbp work fine for
> most of the displays.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Cc: David Ung <davidu@nvidia.com>
> Cc: Antonino A. Daplas <adaplas@gmail.com>
> ---
> drivers/video/fbdev/core/fbcvt.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/video/fbdev/core/fbcvt.c
> b/drivers/video/fbdev/core/fbcvt.c
> index 7cb715dfc0e1..55d2bd0ce5c0 100644
> --- a/drivers/video/fbdev/core/fbcvt.c
> +++ b/drivers/video/fbdev/core/fbcvt.c
> @@ -369,9 +369,9 @@ int fb_find_mode_cvt(struct fb_videomode *mode,
> int margins, int rb)
> cvt.h_back_porch = cvt.hblank/2 + cvt.h_margin;
> cvt.h_front_porch = cvt.hblank - cvt.hsync - cvt.h_back_porch +
> 2 * cvt.h_margin;
> - cvt.v_back_porch = 3 + cvt.v_margin;
> - cvt.v_front_porch = cvt.vtotal - cvt.yres/cvt.interlace -
> - cvt.v_back_porch - cvt.vsync;
> + cvt.v_front_porch = 3 + cvt.v_margin;
> + cvt.v_back_porch = cvt.vtotal - cvt.yres/cvt.interlace -
> + cvt.v_front_porch - cvt.vsync;
> fb_cvt_print_name(&cvt);
> fb_cvt_convert_to_mode(&cvt, mode);
>
> --
> 2.2.2
lgtm
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prev parent reply other threads:[~2015-01-26 20:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-26 13:10 [PATCH] fbdev: fix CVT vertical front and back porch values Tomi Valkeinen
2015-01-26 20:21 ` David Ung [this message]
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