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From:   Kaaira Gupta <kgupta@es.iitr.ac.in>
To:     Helen Koike <helen.koike@collabora.com>,
        Shuah Khan <skhan@linuxfoundation.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        Kieran Bingham <kieran.bingham@ideasonboard.com>,
        =?UTF-8?q?Niklas=20S=C3=B6derlund?= <niklas.soderlund@ragnatech.se>
Cc:     Kaaira Gupta <kgupta@es.iitr.ac.in>
Subject: [PATCH v2 1/3] media: vimc: Add usage count to subdevices
Date:   Fri, 24 Jul 2020 17:32:11 +0530
Message-Id: <20200724120213.17119-2-kgupta@es.iitr.ac.in>
In-Reply-To: <20200724120213.17119-1-kgupta@es.iitr.ac.in>
References: <20200724120213.17119-1-kgupta@es.iitr.ac.in>
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Sender: linux-kernel-owner@vger.kernel.org
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Prepare for multiple video streams from the same sensor by adding a use
counter to each subdevice. The counter is increased for every s_stream(1)
and decremented for every s_stream(0) call.

The subdevice stream is not started or stopped unless the usage count go
from 0 to 1 (started) or from 1 to 0 (stopped). This allows for multiple
s_stream() calls to try to either start or stop the device while only
the first/last call will actually effect the state of the device.

[Kaaira: rebased the patch on current HEAD of media-tree
(8f2a4a9d5ff5202d0b3e3a144ebb9b67aabadd29)]

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Signed-off-by: Kaaira Gupta <kgupta@es.iitr.ac.in>
---
 drivers/media/test-drivers/vimc/vimc-debayer.c | 8 ++++++++
 drivers/media/test-drivers/vimc/vimc-scaler.c  | 8 ++++++++
 drivers/media/test-drivers/vimc/vimc-sensor.c  | 9 ++++++++-
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/media/test-drivers/vimc/vimc-debayer.c b/drivers/media/test-drivers/vimc/vimc-debayer.c
index c3f6fef34f68..93fe19d8d2b4 100644
--- a/drivers/media/test-drivers/vimc/vimc-debayer.c
+++ b/drivers/media/test-drivers/vimc/vimc-debayer.c
@@ -29,6 +29,7 @@ struct vimc_deb_pix_map {
 struct vimc_deb_device {
 	struct vimc_ent_device ved;
 	struct v4l2_subdev sd;
+	atomic_t use_count;
 	/* The active format */
 	struct v4l2_mbus_framefmt sink_fmt;
 	u32 src_code;
@@ -343,6 +344,9 @@ static int vimc_deb_s_stream(struct v4l2_subdev *sd, int enable)
 		const struct vimc_pix_map *vpix;
 		unsigned int frame_size;
 
+		if (atomic_inc_return(&vdeb->use_count) != 1)
+			return 0;
+
 		if (vdeb->src_frame)
 			return 0;
 
@@ -368,6 +372,9 @@ static int vimc_deb_s_stream(struct v4l2_subdev *sd, int enable)
 			return -ENOMEM;
 
 	} else {
+		if (atomic_dec_return(&vdeb->use_count) != 0)
+			return 0;
+
 		if (!vdeb->src_frame)
 			return 0;
 
@@ -595,6 +602,7 @@ static struct vimc_ent_device *vimc_deb_add(struct vimc_device *vimc,
 	vdeb->ved.process_frame = vimc_deb_process_frame;
 	vdeb->ved.dev = vimc->mdev.dev;
 	vdeb->mean_win_size = vimc_deb_ctrl_mean_win_size.def;
+	atomic_set(&vdeb->use_count, 0);
 
 	/* Initialize the frame format */
 	vdeb->sink_fmt = sink_fmt_default;
diff --git a/drivers/media/test-drivers/vimc/vimc-scaler.c b/drivers/media/test-drivers/vimc/vimc-scaler.c
index 121fa7d62a2e..9b8458dbe57c 100644
--- a/drivers/media/test-drivers/vimc/vimc-scaler.c
+++ b/drivers/media/test-drivers/vimc/vimc-scaler.c
@@ -25,6 +25,7 @@ MODULE_PARM_DESC(sca_mult, " the image size multiplier");
 struct vimc_sca_device {
 	struct vimc_ent_device ved;
 	struct v4l2_subdev sd;
+	atomic_t use_count;
 	/* NOTE: the source fmt is the same as the sink
 	 * with the width and hight multiplied by mult
 	 */
@@ -340,6 +341,9 @@ static int vimc_sca_s_stream(struct v4l2_subdev *sd, int enable)
 		const struct vimc_pix_map *vpix;
 		unsigned int frame_size;
 
+		if (atomic_inc_return(&vsca->use_count) != 1)
+			return 0;
+
 		if (vsca->src_frame)
 			return 0;
 
@@ -363,6 +367,9 @@ static int vimc_sca_s_stream(struct v4l2_subdev *sd, int enable)
 			return -ENOMEM;
 
 	} else {
+		if (atomic_dec_return(&vsca->use_count) != 0)
+			return 0;
+
 		if (!vsca->src_frame)
 			return 0;
 
@@ -506,6 +513,7 @@ static struct vimc_ent_device *vimc_sca_add(struct vimc_device *vimc,
 
 	vsca->ved.process_frame = vimc_sca_process_frame;
 	vsca->ved.dev = vimc->mdev.dev;
+	atomic_set(&vsca->use_count, 0);
 
 	/* Initialize the frame format */
 	vsca->sink_fmt = sink_fmt_default;
diff --git a/drivers/media/test-drivers/vimc/vimc-sensor.c b/drivers/media/test-drivers/vimc/vimc-sensor.c
index ba5db5a150b4..dbe169604e71 100644
--- a/drivers/media/test-drivers/vimc/vimc-sensor.c
+++ b/drivers/media/test-drivers/vimc/vimc-sensor.c
@@ -24,6 +24,7 @@ struct vimc_sen_device {
 	struct vimc_ent_device ved;
 	struct v4l2_subdev sd;
 	struct tpg_data tpg;
+	atomic_t use_count;
 	u8 *frame;
 	enum vimc_sen_osd_mode osd_value;
 	u64 start_stream_ts;
@@ -250,8 +251,10 @@ static int vimc_sen_s_stream(struct v4l2_subdev *sd, int enable)
 		const struct vimc_pix_map *vpix;
 		unsigned int frame_size;
 
-		vsen->start_stream_ts = ktime_get_ns();
+		if (atomic_inc_return(&vsen->use_count) != 1)
+			return 0;
 
+		vsen->start_stream_ts = ktime_get_ns();
 		/* Calculate the frame size */
 		vpix = vimc_pix_map_by_code(vsen->mbus_format.code);
 		frame_size = vsen->mbus_format.width * vpix->bpp *
@@ -270,6 +273,9 @@ static int vimc_sen_s_stream(struct v4l2_subdev *sd, int enable)
 
 	} else {
 
+		if (atomic_dec_return(&vsen->use_count) != 0)
+			return 0;
+
 		vfree(vsen->frame);
 		vsen->frame = NULL;
 	}
@@ -430,6 +436,7 @@ static struct vimc_ent_device *vimc_sen_add(struct vimc_device *vimc,
 
 	vsen->ved.process_frame = vimc_sen_process_frame;
 	vsen->ved.dev = vimc->mdev.dev;
+	atomic_set(&vsen->use_count, 0);
 
 	/* Initialize the frame format */
 	vsen->mbus_format = fmt_default;
-- 
2.17.1