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From:   Fabio Estevam <festevam@gmail.com>
Date:   Thu, 17 Jan 2019 18:20:30 -0200
Message-ID: <CAOMZO5BtS_iLcUH0zO1u_L+jVCena-WzRJgR3NUif7UoxQAYVw@mail.gmail.com>
Subject: Re: [PATCH 1/2] media: imx: csi: Disable CSI immediately after last EOF
To:     Steve Longerbeam <slongerbeam@gmail.com>
Cc:     linux-media <linux-media@vger.kernel.org>,
        "open list:STAGING SUBSYSTEM" <devel@driverdev.osuosl.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        open list <linux-kernel@vger.kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Mauro Carvalho Chehab <mchehab@kernel.org>
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Hi Steve,

On Thu, Jan 17, 2019 at 6:15 PM Steve Longerbeam <slongerbeam@gmail.com> wr=
ote:
>
> Disable the CSI immediately after receiving the last EOF before stream
> off (and thus before disabling the IDMA channel).
>
> This fixes a complete system hard lockup on the SabreAuto when streaming
> from the ADV7180, by repeatedly sending a stream off immediately followed
> by stream on:
>
> while true; do v4l2-ctl  -d4 --stream-mmap --stream-count=3D3; done
>
> Eventually this either causes the system lockup or EOF timeouts at all
> subsequent stream on, until a system reset.
>
> The lockup occurs when disabling the IDMA channel at stream off. Disablin=
g
> the CSI before disabling the IDMA channel appears to be a reliable fix fo=
r
> the hard lockup.
>
> Reported-by: Ga=C3=ABl PORTAY <gael.portay@collabora.com>
> Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>

Thanks. Since this fixes a lockup, maybe it is worth adding a Fixes
tag and Cc stable?

> ---
>  drivers/staging/media/imx/imx-media-csi.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/=
media/imx/imx-media-csi.c
> index e18f58f56dfb..9218372cb997 100644
> --- a/drivers/staging/media/imx/imx-media-csi.c
> +++ b/drivers/staging/media/imx/imx-media-csi.c
> @@ -681,6 +681,8 @@ static void csi_idmac_stop(struct csi_priv *priv)
>         if (ret =3D=3D 0)
>                 v4l2_warn(&priv->sd, "wait last EOF timeout\n");
>
> +       ipu_csi_disable(priv->csi);
> +
>         devm_free_irq(priv->dev, priv->eof_irq, priv);
>         devm_free_irq(priv->dev, priv->nfb4eof_irq, priv);
>
> @@ -793,11 +795,10 @@ static void csi_stop(struct csi_priv *priv)
>                 /* stop the frame interval monitor */
>                 if (priv->fim)
>                         imx_media_fim_set_stream(priv->fim, NULL, false);
> +       } else {
> +               ipu_csi_disable(priv->csi);
>         }
> -
> -       ipu_csi_disable(priv->csi);
>  }
> -

Unneeded line removal.