linux-kernel - [PATCH] media: nxp: imx8-isi: add m2m usage

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Message-Id: <20240920142715.2246323-1-laurentiu.palcu@oss.nxp.com>
Date: Fri, 20 Sep 2024 17:27:15 +0300
From: Laurentiu Palcu <laurentiu.palcu@....nxp.com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	Guoniu Zhou <guoniu.zhou@....com>,
	Jacopo Mondi <jacopo@...ndi.org>,
	Christian Hemp <c.hemp@...tec.de>
Cc: Laurentiu Palcu <laurentiu.palcu@....nxp.com>,
	Stefan Riedmueller <s.riedmueller@...tec.de>,
	linux-media@...r.kernel.org,
	imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] media: nxp: imx8-isi: add m2m usage_count check in streamoff

Currently, if streamon/streamoff calls are imbalanced we can end up
with a negative ISI m2m usage_count. When that happens, the next
streamon call will not enable the ISI m2m channel.

So, instead of throwing a warning in streamoff when usage_count drops
below 0, just make sure we don't get there.

Fixes: cf21f328fcafac ("media: nxp: Add i.MX8 ISI driver")
Signed-off-by: Laurentiu Palcu <laurentiu.palcu@....nxp.com>
---
 drivers/media/platform/nxp/imx8-isi/imx8-isi-m2m.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-m2m.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-m2m.c
index 9745d6219a166..b71195a3ba256 100644
--- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-m2m.c
+++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-m2m.c
@@ -575,6 +575,9 @@ static int mxc_isi_m2m_streamoff(struct file *file, void *fh,
 
 	mutex_lock(&m2m->lock);
 
+	if (m2m->usage_count == 0)
+		goto unlock;
+
 	/*
 	 * If the last context is this one, reset it to make sure the device
 	 * will be reconfigured when streaming is restarted.
@@ -594,8 +597,7 @@ static int mxc_isi_m2m_streamoff(struct file *file, void *fh,
 		mxc_isi_channel_release(m2m->pipe);
 	}
 
-	WARN_ON(m2m->usage_count < 0);
-
+unlock:
 	mutex_unlock(&m2m->lock);
 
 	return 0;
-- 
2.34.1