media: imx: csi: Disable CSI immediately after last EOF

commit 2e0fe66e upstream.

Disable the CSI immediately after receiving the last EOF before stream
off (and thus before disabling the IDMA channel). Do this by moving the
wait for EOF completion into a new function csi_idmac_wait_last_eof().

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: 4a34ec8e ("[media] media: imx: Add CSI subdev driver")
Reported-by: Gaël PORTAY <gael.portay@collabora.com>
Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
Cc: stable@vger.kernel.org	# for 4.13 and up
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/media/imx/imx-media-csi.c

@@ -538,7 +538,7 @@ static int csi_idmac_start(struct csi_priv *priv)
 	return ret;
 }
 
-static void csi_idmac_stop(struct csi_priv *priv)
+static void csi_idmac_wait_last_eof(struct csi_priv *priv)
 {
 	unsigned long flags;
 	int ret;
@@ -555,7 +555,10 @@ static void csi_idmac_stop(struct csi_priv *priv)
 		&priv->last_eof_comp, msecs_to_jiffies(IMX_MEDIA_EOF_TIMEOUT));
 	if (ret == 0)
 		v4l2_warn(&priv->sd, "wait last EOF timeout\n");
+}
 
+static void csi_idmac_stop(struct csi_priv *priv)
+{
 	devm_free_irq(priv->dev, priv->eof_irq, priv);
 	devm_free_irq(priv->dev, priv->nfb4eof_irq, priv);
 
@@ -681,6 +684,16 @@ static int csi_start(struct csi_priv *priv)
 
 static void csi_stop(struct csi_priv *priv)
 {
+	if (priv->dest == IPU_CSI_DEST_IDMAC)
+		csi_idmac_wait_last_eof(priv);
+
+	/*
+	 * Disable the CSI asap, after syncing with the last EOF.
+	 * Doing so after the IDMA channel is disabled has shown to
+	 * create hard system-wide hangs.
+	 */
+	ipu_csi_disable(priv->csi);
+
 	if (priv->dest == IPU_CSI_DEST_IDMAC) {
 		csi_idmac_stop(priv);
 
@@ -688,8 +701,6 @@ static void csi_stop(struct csi_priv *priv)
 		if (priv->fim)
 			imx_media_fim_set_stream(priv->fim, NULL, false);
 	}
-
-	ipu_csi_disable(priv->csi);
 }
 
 static const struct csi_skip_desc csi_skip[12] = {