[PATCH v4 1/3] media: imx: csi: Disable CSI immediately after last EOF

[Steve Longerbeam <slongerbeam@gmail.com>]

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: 4a34ec8e470cb ("[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
---
Changes in v4:
- Disabling SMFC will have no effect if both CSI's are streaming. So
  go back to disabling CSI before channel as in v2, but split up
  csi_idmac_stop such that ipu_csi_disable can still be called within
  csi_stop.
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 | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c
index 7abfe0aa1418..920e38885292 100644
--- a/drivers/staging/media/imx/imx-media-csi.c
+++ b/drivers/staging/media/imx/imx-media-csi.c
@@ -662,7 +662,7 @@ 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;
@@ -679,7 +679,10 @@ 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);
 
@@ -786,6 +789,16 @@ 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);
 
@@ -793,8 +806,6 @@ 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] = {
-- 
2.17.1