linux-kernel - [PATCH v3 1/2] media: imx: csi: Disable SMFC before disabling IDMA channel

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Date:   Fri, 18 Jan 2019 17:04:56 -0800
From:   Steve Longerbeam <slongerbeam@...il.com>
To:     linux-media@...r.kernel.org
Cc:     Gael PORTAY <gael.portay@...labora.com>,
        Peter Seiderer <ps.report@....net>,
        Steve Longerbeam <slongerbeam@...il.com>,
        stable@...r.kernel.org, Philipp Zabel <p.zabel@...gutronix.de>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devel@...verdev.osuosl.org (open list:STAGING SUBSYSTEM),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v3 1/2] media: imx: csi: Disable SMFC before disabling IDMA channel

Disable the SMFC before disabling the IDMA channel, instead of after,
in csi_idmac_unsetup().

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. Stopping
the video data stream entering the IDMA channel before disabling the
channel itself appears to be a reliable fix for the hard lockup. That can
be done either by disabling the SMFC or the CSI before disabling the
channel. Disabling the SMFC before the channel is the easiest solution,
so do that.

Fixes: 4a34ec8e470cb ("[media] media: imx: Add CSI subdev driver")

Suggested-by: Peter Seiderer <ps.report@....net>
Reported-by: Gaël PORTAY <gael.portay@...labora.com>
Signed-off-by: Steve Longerbeam <slongerbeam@...il.com>
Cc: stable@...r.kernel.org
---
Changes in v3:
- switch from disabling the CSI before the channel to disabling the
  SMFC before the channel.
Changes in v2:
- restore an empty line
- Add Fixes: and Cc: stable
---
 drivers/staging/media/imx/imx-media-csi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c
index e18f58f56dfb..8610027eac97 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);
 }
-- 
2.17.1