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From:   Steve Longerbeam <slongerbeam@gmail.com>
To:     linux-media@vger.kernel.org
Cc:     Steve Longerbeam <slongerbeam@gmail.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        devel@driverdev.osuosl.org (open list:STAGING SUBSYSTEM),
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH 1/2] media: imx: csi: Disable CSI immediately after last EOF
Date:   Thu, 17 Jan 2019 12:13:46 -0800
Message-Id: <20190117201347.27347-2-slongerbeam@gmail.com>
In-Reply-To: <20190117201347.27347-1-slongerbeam@gmail.com>
References: <20190117201347.27347-1-slongerbeam@gmail.com>
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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.

Reported-by: Gaël PORTAY <gael.portay@collabora.com>
Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
---
 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 == 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);
 }
-
 static const struct csi_skip_desc csi_skip[12] = {
 	{ 1, 1, 0x00 }, /* Keep all frames */
 	{ 5, 6, 0x10 }, /* Skip every sixth frame */
-- 
2.17.1