linux-kernel - Re: [PATCH] drm/sun4i: fix HSYNC and VSYNC polarity

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Date:   Thu, 6 Dec 2018 18:29:00 +1100
From:   Jonathan Liu <net147@...il.com>
To:     Giulio Benetti <giulio.benetti@...ronovasrl.com>
Cc:     Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/sun4i: fix HSYNC and VSYNC polarity

Hi Giulio,

On Thu, 15 Feb 2018 at 17:54, Giulio Benetti
<giulio.benetti@...ronovasrl.com> wrote:
>
> Differently from other Lcd signals, HSYNC and VSYNC signals
> result inverted if their bits are cleared to 0.
>
> Invert their settings of IO_POL register.
>
> Signed-off-by: Giulio Benetti <giulio.benetti@...ronovasrl.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 3c15cf2..aaf911a 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -389,10 +389,10 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
>                      SUN4I_TCON0_BASIC3_H_SYNC(hsync));
>
>         /* Setup the polarity of the various signals */
> -       if (!(mode->flags & DRM_MODE_FLAG_PHSYNC))
> +       if (mode->flags & DRM_MODE_FLAG_PHSYNC)
>                 val |= SUN4I_TCON0_IO_POL_HSYNC_POSITIVE;
>
> -       if (!(mode->flags & DRM_MODE_FLAG_PVSYNC))
> +       if (mode->flags & DRM_MODE_FLAG_PVSYNC)
>                 val |= SUN4I_TCON0_IO_POL_VSYNC_POSITIVE;
>
>         regmap_update_bits(tcon->regs, SUN4I_TCON0_IO_POL_REG,

I am running Linux 4.19.6 and noticed with Olimex LCD-OLinuXino-7TS 7"
LCD touchscreen (Innolux AT070TN92) connected to Olimex
A20-OLinuXino-MICRO that the image does not display correctly after
this change.
The image is shifted to the right.

Reverting the change results in the image being displayed correctly on
the screen.

I have in the device tree a "panel" node with compatible =
"innolux,at070tn92" which uses the timings in
drivers/gpu/drm/panel/panel-simple.c.

Any ideas?

Thanks.

Regards,
Jonathan