Re: [v2,1/2] media: imx: csi: Disable CSI immediately after last EOF

[Peter Seiderer <ps.report@gmx.net>]

Hello Steve,

On Thu, Jan 17, 2019 at 6:15 PM Steve Longerbeam <slongerbeam@gmail.com> wrote:
>
> 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=3; 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. Disabling
> the CSI before disabling the IDMA channel appears to be a reliable fix for
> the hard lockup.
> 
> Fixes: 4a34ec8e470cb ("[media] media: imx: Add CSI subdev driver")
[...]

Similar lockup observed on a custom i.mx6 board, fixed locally by the following
patch/workaround:

diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c
index 555aa45e02e3..f04d1695f7a4 100644
--- a/drivers/staging/media/imx/imx-media-csi.c
+++ b/drivers/staging/media/imx/imx-media-csi.c
@@ -560,8 +560,8 @@ static int csi_idmac_setup_channel(struct csi_priv *priv)
 static void csi_idmac_unsetup(struct csi_priv *priv,
                              enum vb2_buffer_state state)
 {
-       ipu_idmac_disable_channel(priv->idmac_ch);
        ipu_smfc_disable(priv->smfc);
+       ipu_idmac_disable_channel(priv->idmac_ch);

        csi_idmac_unsetup_vb2_buf(priv, state);
 }

Will test your patch the next days...

Regards,
Peter

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