Re: [PATCH 2/2] drm/bridge: lt9611: Do not generate HFP/HBP/HSA and EOT packet

From: Amit Pundir <amit.pundir@linaro.org>
To: Marek Vasut <marex@denx.de>
Cc: dri-devel@lists.freedesktop.org,
	 Neil Armstrong <neil.armstrong@linaro.org>,
	Robert Foss <rfoss@kernel.org>,
	 Andrzej Hajda <andrzej.hajda@intel.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	 Jernej Skrabec <jernej.skrabec@gmail.com>,
	Michael Walle <michael@walle.cc>,
	 Jagan Teki <jagan@amarulasolutions.com>,
	 Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	 Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	 Linux regressions mailing list <regressions@lists.linux.dev>
Subject: Re: [PATCH 2/2] drm/bridge: lt9611: Do not generate HFP/HBP/HSA and EOT packet
Date: Wed, 5 Jul 2023 10:15:01 +0530	[thread overview]
Message-ID: <CAMi1Hd0TD=2z_=bcDrht3H_wiLvAFcv8Z-U_r_KUOoeMc6UMjw@mail.gmail.com> (raw)
In-Reply-To: <20230403221233.500485-2-marex@denx.de>

Hi Marek,

On Wed, 5 Jul 2023 at 01:48, Marek Vasut <marex@denx.de> wrote:
>
> Do not generate the HS front and back porch gaps, the HSA gap and
> EOT packet, as these packets are not required. This makes the bridge
> work with Samsung DSIM on i.MX8MM and i.MX8MP.

This patch broke display on Dragonboard 845c (SDM845) devboard running
AOSP. This is what I see
https://people.linaro.org/~amit.pundir/db845c-userdebug/v6.5-broken-display/PXL_20230704_150156326.jpg.
Reverting this patch fixes this regression for me.

Regards,
Amit Pundir

>
> Signed-off-by: Marek Vasut <marex@denx.de>
> ---
> Cc: Andrzej Hajda <andrzej.hajda@intel.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: David Airlie <airlied@gmail.com>
> Cc: Jagan Teki <jagan@amarulasolutions.com>
> Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
> Cc: Jonas Karlman <jonas@kwiboo.se>
> Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
> Cc: Michael Walle <michael@walle.cc>
> Cc: Neil Armstrong <neil.armstrong@linaro.org>
> Cc: Robert Foss <rfoss@kernel.org>
> Cc: dri-devel@lists.freedesktop.org
> ---
>  drivers/gpu/drm/bridge/lontium-lt9611.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/lontium-lt9611.c b/drivers/gpu/drm/bridge/lontium-lt9611.c
> index a25d21a7d5c19..151efe92711c4 100644
> --- a/drivers/gpu/drm/bridge/lontium-lt9611.c
> +++ b/drivers/gpu/drm/bridge/lontium-lt9611.c
> @@ -774,7 +774,9 @@ static struct mipi_dsi_device *lt9611_attach_dsi(struct lt9611 *lt9611,
>         dsi->lanes = 4;
>         dsi->format = MIPI_DSI_FMT_RGB888;
>         dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_SYNC_PULSE |
> -                         MIPI_DSI_MODE_VIDEO_HSE;
> +                         MIPI_DSI_MODE_VIDEO_HSE | MIPI_DSI_MODE_VIDEO_NO_HSA |
> +                         MIPI_DSI_MODE_VIDEO_NO_HFP | MIPI_DSI_MODE_VIDEO_NO_HBP |
> +                         MIPI_DSI_MODE_NO_EOT_PACKET;
>
>         ret = devm_mipi_dsi_attach(dev, dsi);
>         if (ret < 0) {
> --
> 2.39.2
>