[PATCH v2] media: sun8i-a83t-mipi-csi2: Use V4L2 subdev active state

[PATCH v2] media: sun8i-a83t-mipi-csi2: Use V4L2 subdev active state

[Arash Golgol]

Use the V4L2 subdev active state API to store the active format.
This simplifies the driver not only by dropping the bridge mbus_format
field, but it also allows dropping the bridge lock, replaced with
the state lock.

The sun8i-a83t-mipi-csi2 hardware does not perform any format
conversion. Enforce identical formats on the sink and source pads in
the set_fmt() and init_state() callbacks.

Signed-off-by: Arash Golgol <arash.golgol@gmail.com>
---
Changes in v2:
 - Initialize active state before calling v4l2_subdev_state_get_format()
 - Fix line wrapping reported by checkpatch
 - Link to media-ci report: https://linux-media.pages.freedesktop.org/-/users/patchwork/-/jobs/99865145/artifacts/report.htm

 .../sun8i_a83t_mipi_csi2.c                    | 111 +++++++++---------
 .../sun8i_a83t_mipi_csi2.h                    |   2 -
 2 files changed, 55 insertions(+), 58 deletions(-)

diff --git a/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c b/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c
index dbc51daa4fe3..743bc86bfeab 100644
--- a/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c
+++ b/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c
@@ -144,12 +144,12 @@ sun8i_a83t_mipi_csi2_disable(struct sun8i_a83t_mipi_csi2_device *csi2_dev)
 }
 
 static void
-sun8i_a83t_mipi_csi2_configure(struct sun8i_a83t_mipi_csi2_device *csi2_dev)
+sun8i_a83t_mipi_csi2_configure(struct sun8i_a83t_mipi_csi2_device *csi2_dev,
+			       const struct v4l2_mbus_framefmt *mbus_format)
 {
 	struct regmap *regmap = csi2_dev->regmap;
 	unsigned int lanes_count =
 		csi2_dev->bridge.endpoint.bus.mipi_csi2.num_data_lanes;
-	struct v4l2_mbus_framefmt *mbus_format = &csi2_dev->bridge.mbus_format;
 	const struct sun8i_a83t_mipi_csi2_format *format;
 	struct device *dev = csi2_dev->dev;
 	u32 version = 0;
@@ -205,7 +205,8 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
 	struct v4l2_subdev *source_subdev = csi2_dev->bridge.source_subdev;
 	union phy_configure_opts dphy_opts = { 0 };
 	struct phy_configure_opts_mipi_dphy *dphy_cfg = &dphy_opts.mipi_dphy;
-	struct v4l2_mbus_framefmt *mbus_format = &csi2_dev->bridge.mbus_format;
+	struct v4l2_subdev_state *state;
+	const struct v4l2_mbus_framefmt *mbus_format;
 	const struct sun8i_a83t_mipi_csi2_format *format;
 	struct phy *dphy = csi2_dev->dphy;
 	struct device *dev = csi2_dev->dev;
@@ -215,8 +216,12 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
 	unsigned long pixel_rate;
 	int ret;
 
-	if (!source_subdev)
-		return -ENODEV;
+	state = v4l2_subdev_lock_and_get_active_state(subdev);
+
+	if (!source_subdev) {
+		ret = -ENODEV;
+		goto unlock;
+	}
 
 	if (!on) {
 		v4l2_subdev_call(source_subdev, video, s_stream, 0);
@@ -254,6 +259,9 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
 		goto error_pm;
 	}
 
+	mbus_format =
+		v4l2_subdev_state_get_format(state,
+					     SUN8I_A83T_MIPI_CSI2_PAD_SINK);
 	format = sun8i_a83t_mipi_csi2_format_find(mbus_format->code);
 	if (WARN_ON(!format)) {
 		ret = -ENODEV;
@@ -292,7 +300,7 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
 
 	/* Controller */
 
-	sun8i_a83t_mipi_csi2_configure(csi2_dev);
+	sun8i_a83t_mipi_csi2_configure(csi2_dev, mbus_format);
 	sun8i_a83t_mipi_csi2_enable(csi2_dev);
 
 	/* D-PHY */
@@ -309,7 +317,8 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
 	if (ret && ret != -ENOIOCTLCMD)
 		goto disable;
 
-	return 0;
+	ret = 0;
+	goto unlock;
 
 disable:
 	phy_power_off(dphy);
@@ -318,6 +327,8 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
 error_pm:
 	pm_runtime_put(dev);
 
+unlock:
+	v4l2_subdev_unlock_state(state);
 	return ret;
 }
 
@@ -341,22 +352,24 @@ sun8i_a83t_mipi_csi2_mbus_format_prepare(struct v4l2_mbus_framefmt *mbus_format)
 static int sun8i_a83t_mipi_csi2_init_state(struct v4l2_subdev *subdev,
 					   struct v4l2_subdev_state *state)
 {
-	struct sun8i_a83t_mipi_csi2_device *csi2_dev =
-		v4l2_get_subdevdata(subdev);
-	unsigned int pad = SUN8I_A83T_MIPI_CSI2_PAD_SINK;
-	struct v4l2_mbus_framefmt *mbus_format =
-		v4l2_subdev_state_get_format(state, pad);
-	struct mutex *lock = &csi2_dev->bridge.lock;
+	unsigned int pad;
+
+	/*
+	 * This subdev does not perform format conversion,
+	 * initialize both pads identically.
+	 */
+	for (pad = 0; pad < subdev->entity.num_pads; pad++) {
+		struct v4l2_mbus_framefmt *mbus_format;
 
-	mutex_lock(lock);
+		mbus_format = v4l2_subdev_state_get_format(state, pad);
 
-	mbus_format->code = sun8i_a83t_mipi_csi2_formats[0].mbus_code;
-	mbus_format->width = 640;
-	mbus_format->height = 480;
+		mbus_format->code = sun8i_a83t_mipi_csi2_formats[0].mbus_code;
+		mbus_format->width = 640;
+		mbus_format->height = 480;
 
-	sun8i_a83t_mipi_csi2_mbus_format_prepare(mbus_format);
+		sun8i_a83t_mipi_csi2_mbus_format_prepare(mbus_format);
+	}
 
-	mutex_unlock(lock);
 
 	return 0;
 }
@@ -375,55 +388,33 @@ sun8i_a83t_mipi_csi2_enum_mbus_code(struct v4l2_subdev *subdev,
 	return 0;
 }
 
-static int sun8i_a83t_mipi_csi2_get_fmt(struct v4l2_subdev *subdev,
-					struct v4l2_subdev_state *state,
-					struct v4l2_subdev_format *format)
-{
-	struct sun8i_a83t_mipi_csi2_device *csi2_dev =
-		v4l2_get_subdevdata(subdev);
-	struct v4l2_mbus_framefmt *mbus_format = &format->format;
-	struct mutex *lock = &csi2_dev->bridge.lock;
-
-	mutex_lock(lock);
-
-	if (format->which == V4L2_SUBDEV_FORMAT_TRY)
-		*mbus_format = *v4l2_subdev_state_get_format(state,
-							     format->pad);
-	else
-		*mbus_format = csi2_dev->bridge.mbus_format;
-
-	mutex_unlock(lock);
-
-	return 0;
-}
-
 static int sun8i_a83t_mipi_csi2_set_fmt(struct v4l2_subdev *subdev,
 					struct v4l2_subdev_state *state,
 					struct v4l2_subdev_format *format)
 {
-	struct sun8i_a83t_mipi_csi2_device *csi2_dev =
-		v4l2_get_subdevdata(subdev);
-	struct v4l2_mbus_framefmt *mbus_format = &format->format;
-	struct mutex *lock = &csi2_dev->bridge.lock;
+	struct v4l2_mbus_framefmt *fmt;
 
-	mutex_lock(lock);
+	/* The format on the source pad always matches the sink pad. */
+	if (format->pad != SUN8I_A83T_MIPI_CSI2_PAD_SINK)
+		return v4l2_subdev_get_fmt(subdev, state, format);
 
-	sun8i_a83t_mipi_csi2_mbus_format_prepare(mbus_format);
+	sun8i_a83t_mipi_csi2_mbus_format_prepare(&format->format);
 
-	if (format->which == V4L2_SUBDEV_FORMAT_TRY)
-		*v4l2_subdev_state_get_format(state, format->pad) =
-			*mbus_format;
-	else
-		csi2_dev->bridge.mbus_format = *mbus_format;
+	/* Set the format on the sink pad. */
+	fmt = v4l2_subdev_state_get_format(state, format->pad);
+	*fmt = format->format;
 
-	mutex_unlock(lock);
+	/* Propagate the format to the source pad. */
+	fmt = v4l2_subdev_state_get_format(state,
+					   SUN8I_A83T_MIPI_CSI2_PAD_SOURCE);
+	*fmt = format->format;
 
 	return 0;
 }
 
 static const struct v4l2_subdev_pad_ops sun8i_a83t_mipi_csi2_pad_ops = {
 	.enum_mbus_code	= sun8i_a83t_mipi_csi2_enum_mbus_code,
-	.get_fmt	= sun8i_a83t_mipi_csi2_get_fmt,
+	.get_fmt	= v4l2_subdev_get_fmt,
 	.set_fmt	= sun8i_a83t_mipi_csi2_set_fmt,
 };
 
@@ -540,8 +531,6 @@ sun8i_a83t_mipi_csi2_bridge_setup(struct sun8i_a83t_mipi_csi2_device *csi2_dev)
 	bool notifier_registered = false;
 	int ret;
 
-	mutex_init(&bridge->lock);
-
 	/* V4L2 Subdev */
 
 	v4l2_subdev_init(subdev, &sun8i_a83t_mipi_csi2_subdev_ops);
@@ -570,6 +559,12 @@ sun8i_a83t_mipi_csi2_bridge_setup(struct sun8i_a83t_mipi_csi2_device *csi2_dev)
 	if (ret)
 		return ret;
 
+	/* V4L2 Subdev finalize */
+
+	ret = v4l2_subdev_init_finalize(subdev);
+	if (ret < 0)
+		goto error_media_entity_cleanup;
+
 	/* V4L2 Async */
 
 	v4l2_async_subdev_nf_init(notifier, subdev);
@@ -603,6 +598,9 @@ sun8i_a83t_mipi_csi2_bridge_setup(struct sun8i_a83t_mipi_csi2_device *csi2_dev)
 error_v4l2_notifier_cleanup:
 	v4l2_async_nf_cleanup(notifier);
 
+	v4l2_subdev_cleanup(subdev);
+
+error_media_entity_cleanup:
 	media_entity_cleanup(&subdev->entity);
 
 	return ret;
@@ -617,6 +615,7 @@ sun8i_a83t_mipi_csi2_bridge_cleanup(struct sun8i_a83t_mipi_csi2_device *csi2_dev
 	v4l2_async_unregister_subdev(subdev);
 	v4l2_async_nf_unregister(notifier);
 	v4l2_async_nf_cleanup(notifier);
+	v4l2_subdev_cleanup(subdev);
 	media_entity_cleanup(&subdev->entity);
 }
 
diff --git a/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.h b/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.h
index f1e64c53434c..819527bcd64d 100644
--- a/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.h
+++ b/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.h
@@ -33,8 +33,6 @@ struct sun8i_a83t_mipi_csi2_bridge {
 	struct media_pad		pads[SUN8I_A83T_MIPI_CSI2_PAD_COUNT];
 	struct v4l2_fwnode_endpoint	endpoint;
 	struct v4l2_async_notifier	notifier;
-	struct v4l2_mbus_framefmt	mbus_format;
-	struct mutex			lock; /* Mbus format lock. */
 
 	struct v4l2_subdev		*source_subdev;
 };
-- 
2.34.1

Re: [PATCH v2] media: sun8i-a83t-mipi-csi2: Use V4L2 subdev active state

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The active state lock is leaked in the error path of `pm_runtime_resume_and_get()` within `sun8i_a83t_mipi_csi2_s_stream()`.
--

commit 1aff86a32a5202665d5639183ff47ad585d7b58e
Author: Arash Golgol <arash.golgol@gmail.com>
Subject: media: sun8i-a83t-mipi-csi2: Use V4L2 subdev active state

This commit updates the sun8i-a83t-mipi-csi2 driver to use the V4L2 subdev
active state API. This simplifies format storage and replaces the bridge lock
with the state lock.

> diff --git a/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c b/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c
> index dbc51daa4fe37..743bc86bfeabe 100644
> --- a/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c
> +++ b/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c
[ ... ]
> @@ -215,8 +216,12 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  	unsigned long pixel_rate;
>  	int ret;
>  
> -	if (!source_subdev)
> -		return -ENODEV;
> +	state = v4l2_subdev_lock_and_get_active_state(subdev);
> +
> +	if (!source_subdev) {
> +		ret = -ENODEV;
> +		goto unlock;
> +	}
>  
>  	if (!on) {
>  		v4l2_subdev_call(source_subdev, video, s_stream, 0);

Does this code leak the active state lock if the subsequent runtime PM resume
fails?

Looking at the unmodified code that immediately follows this hunk in
sun8i_a83t_mipi_csi2_s_stream():

	/* Runtime PM */

	ret = pm_runtime_resume_and_get(dev);
	if (ret < 0)
		return ret;

Since the state lock is now acquired at the beginning of the function,
if pm_runtime_resume_and_get() returns a negative value, it directly returns
to the caller.

Because it bypasses the "goto unlock" path, the state lock remains acquired,
which could cause a deadlock on any subsequent attempt to access the active
state or start the stream.

Should this error path be updated to "goto unlock" so the lock is properly
released?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260515144335.61323-1-arash.golgol@gmail.com?part=1