Re: [PATCH v15 17/19] media: v4l2-subdev: Add subdev .(enable|disable)_streams() operations

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On 03.10.2022 15:18, Tomi Valkeinen wrote:
From: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>

Add two new subdev pad operations, .enable_streams() and
.disable_streams(), to allow control of individual streams per pad. This
is a superset of what the video .s_stream() operation implements.

To help with handling of backward compatibility, add two wrapper
functions around those operations, and require their usage in drivers.

Hi, what does it mean 'require their usage in drivers'?
Drivers suppose to call these helpers in the s_stream implementation?

Thanks,
Dafna


Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Reviewed-by: Jacopo Mondi <jacopo@xxxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-subdev.c | 224 ++++++++++++++++++++++++++
include/media/v4l2-subdev.h           |  85 ++++++++++
2 files changed, 309 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index cc8666c5069b..101c1cfc0123 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -1717,6 +1717,230 @@ int v4l2_subdev_routing_validate(struct v4l2_subdev *sd,
}
EXPORT_SYMBOL_GPL(v4l2_subdev_routing_validate);

+static int v4l2_subdev_enable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
+					       u64 streams_mask)
+{
+	struct device *dev = sd->entity.graph_obj.mdev->dev;
+	unsigned int i;
+	int ret;
+
+	/*
+	 * The subdev doesn't implement pad-based stream enable, fall back
+	 * on the .s_stream() operation. This can only be done for subdevs that
+	 * have a single source pad, as sd->enabled_streams is global to the
+	 * subdev.
+	 */
+	if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
+		return -EOPNOTSUPP;
+
+	for (i = 0; i < sd->entity.num_pads; ++i) {
+		if (i != pad && sd->entity.pads[i].flags & MEDIA_PAD_FL_SOURCE)
+			return -EOPNOTSUPP;
+	}
+
+	if (sd->enabled_streams & streams_mask) {
+		dev_dbg(dev, "set of streams %#llx already enabled on %s:%u\n",
+			streams_mask, sd->entity.name, pad);
+		return -EALREADY;
+	}
+
+	/* Start streaming when the first streams are enabled. */
+	if (!sd->enabled_streams) {
+		ret = v4l2_subdev_call(sd, video, s_stream, 1);
+		if (ret)
+			return ret;
+	}
+
+	sd->enabled_streams |= streams_mask;
+
+	return 0;
+}
+
+int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
+			       u64 streams_mask)
+{
+	struct device *dev = sd->entity.graph_obj.mdev->dev;
+	struct v4l2_subdev_state *state;
+	u64 found_streams = 0;
+	unsigned int i;
+	int ret;
+
+	/* A few basic sanity checks first. */
+	if (pad >= sd->entity.num_pads)
+		return -EINVAL;
+
+	if (!streams_mask)
+		return 0;
+
+	/* Fallback on .s_stream() if .enable_streams() isn't available. */
+	if (!sd->ops->pad || !sd->ops->pad->enable_streams)
+		return v4l2_subdev_enable_streams_fallback(sd, pad,
+							   streams_mask);
+
+	state = v4l2_subdev_lock_and_get_active_state(sd);
+
+	/*
+	 * Verify that the requested streams exist and that they are not
+	 * already enabled.
+	 */
+	for (i = 0; i < state->stream_configs.num_configs; ++i) {
+		struct v4l2_subdev_stream_config *cfg =
+			&state->stream_configs.configs[i];
+
+		if (cfg->pad != pad || !(streams_mask & BIT_ULL(cfg->stream)))
+			continue;
+
+		found_streams |= BIT_ULL(cfg->stream);
+
+		if (cfg->enabled) {
+			dev_dbg(dev, "stream %u already enabled on %s:%u\n",
+				cfg->stream, sd->entity.name, pad);
+			ret = -EALREADY;
+			goto done;
+		}
+	}
+
+	if (found_streams != streams_mask) {
+		dev_dbg(dev, "streams 0x%llx not found on %s:%u\n",
+			streams_mask & ~found_streams, sd->entity.name, pad);
+		ret = -EINVAL;
+		goto done;
+	}
+
+	/* Call the .enable_streams() operation. */
+	ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
+			       streams_mask);
+	if (ret)
+		goto done;
+
+	/* Mark the streams as enabled. */
+	for (i = 0; i < state->stream_configs.num_configs; ++i) {
+		struct v4l2_subdev_stream_config *cfg =
+			&state->stream_configs.configs[i];
+
+		if (cfg->pad == pad && (streams_mask & BIT_ULL(cfg->stream)))
+			cfg->enabled = true;
+	}
+
+done:
+	v4l2_subdev_unlock_state(state);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_enable_streams);
+
+static int v4l2_subdev_disable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
+						u64 streams_mask)
+{
+	struct device *dev = sd->entity.graph_obj.mdev->dev;
+	unsigned int i;
+	int ret;
+
+	/*
+	 * If the subdev doesn't implement pad-based stream enable, fall  back
+	 * on the .s_stream() operation. This can only be done for subdevs that
+	 * have a single source pad, as sd->enabled_streams is global to the
+	 * subdev.
+	 */
+	if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
+		return -EOPNOTSUPP;
+
+	for (i = 0; i < sd->entity.num_pads; ++i) {
+		if (i != pad && sd->entity.pads[i].flags & MEDIA_PAD_FL_SOURCE)
+			return -EOPNOTSUPP;
+	}
+
+	if ((sd->enabled_streams & streams_mask) != streams_mask) {
+		dev_dbg(dev, "set of streams %#llx already disabled on %s:%u\n",
+			streams_mask, sd->entity.name, pad);
+		return -EALREADY;
+	}
+
+	/* Stop streaming when the last streams are disabled. */
+	if (!(sd->enabled_streams & ~streams_mask)) {
+		ret = v4l2_subdev_call(sd, video, s_stream, 0);
+		if (ret)
+			return ret;
+	}
+
+	sd->enabled_streams &= ~streams_mask;
+
+	return 0;
+}
+
+int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
+				u64 streams_mask)
+{
+	struct device *dev = sd->entity.graph_obj.mdev->dev;
+	struct v4l2_subdev_state *state;
+	u64 found_streams = 0;
+	unsigned int i;
+	int ret;
+
+	/* A few basic sanity checks first. */
+	if (pad >= sd->entity.num_pads)
+		return -EINVAL;
+
+	if (!streams_mask)
+		return 0;
+
+	/* Fallback on .s_stream() if .disable_streams() isn't available. */
+	if (!sd->ops->pad || !sd->ops->pad->disable_streams)
+		return v4l2_subdev_disable_streams_fallback(sd, pad,
+							    streams_mask);
+
+	state = v4l2_subdev_lock_and_get_active_state(sd);
+
+	/*
+	 * Verify that the requested streams exist and that they are not
+	 * already disabled.
+	 */
+	for (i = 0; i < state->stream_configs.num_configs; ++i) {
+		struct v4l2_subdev_stream_config *cfg =
+			&state->stream_configs.configs[i];
+
+		if (cfg->pad != pad || !(streams_mask & BIT_ULL(cfg->stream)))
+			continue;
+
+		found_streams |= BIT_ULL(cfg->stream);
+
+		if (!cfg->enabled) {
+			dev_dbg(dev, "stream %u already disabled on %s:%u\n",
+				cfg->stream, sd->entity.name, pad);
+			ret = -EALREADY;
+			goto done;
+		}
+	}
+
+	if (found_streams != streams_mask) {
+		dev_dbg(dev, "streams 0x%llx not found on %s:%u\n",
+			streams_mask & ~found_streams, sd->entity.name, pad);
+		ret = -EINVAL;
+		goto done;
+	}
+
+	/* Call the .disable_streams() operation. */
+	ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
+			       streams_mask);
+	if (ret)
+		goto done;
+
+	/* Mark the streams as disabled. */
+	for (i = 0; i < state->stream_configs.num_configs; ++i) {
+		struct v4l2_subdev_stream_config *cfg =
+			&state->stream_configs.configs[i];
+
+		if (cfg->pad == pad && (streams_mask & BIT_ULL(cfg->stream)))
+			cfg->enabled = false;
+	}
+
+done:
+	v4l2_subdev_unlock_state(state);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_disable_streams);
+
#endif /* CONFIG_VIDEO_V4L2_SUBDEV_API */

#endif /* CONFIG_MEDIA_CONTROLLER */
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 8c002d65e08e..bff824367e0b 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -700,6 +700,7 @@ struct v4l2_subdev_pad_config {
 *
 * @pad: pad number
 * @stream: stream number
+ * @enabled: has the stream been enabled with v4l2_subdev_enable_stream()
 * @fmt: &struct v4l2_mbus_framefmt
 * @crop: &struct v4l2_rect to be used for crop
 * @compose: &struct v4l2_rect to be used for compose
@@ -709,6 +710,7 @@ struct v4l2_subdev_pad_config {
struct v4l2_subdev_stream_config {
	u32 pad;
	u32 stream;
+	bool enabled;

	struct v4l2_mbus_framefmt fmt;
	struct v4l2_rect crop;
@@ -814,6 +816,18 @@ struct v4l2_subdev_state {
 *
 * @set_routing: enable or disable data connection routes described in the
 *		 subdevice routing table.
+ *
+ * @enable_streams: Enable the streams defined in streams_mask on the given
+ *	source pad. Subdevs that implement this operation must use the active
+ *	state management provided by the subdev core (enabled through a call to
+ *	v4l2_subdev_init_finalize() at initialization time). Do not call
+ *	directly, use v4l2_subdev_enable_streams() instead.
+ *
+ * @disable_streams: Disable the streams defined in streams_mask on the given
+ *	source pad. Subdevs that implement this operation must use the active
+ *	state management provided by the subdev core (enabled through a call to
+ *	v4l2_subdev_init_finalize() at initialization time). Do not call
+ *	directly, use v4l2_subdev_disable_streams() instead.
 */
struct v4l2_subdev_pad_ops {
	int (*init_cfg)(struct v4l2_subdev *sd,
@@ -860,6 +874,12 @@ struct v4l2_subdev_pad_ops {
			   struct v4l2_subdev_state *state,
			   enum v4l2_subdev_format_whence which,
			   struct v4l2_subdev_krouting *route);
+	int (*enable_streams)(struct v4l2_subdev *sd,
+			      struct v4l2_subdev_state *state, u32 pad,
+			      u64 streams_mask);
+	int (*disable_streams)(struct v4l2_subdev *sd,
+			       struct v4l2_subdev_state *state, u32 pad,
+			       u64 streams_mask);
};

/**
@@ -1005,6 +1025,10 @@ struct v4l2_subdev_platform_data {
 * @active_state: Active state for the subdev (NULL for subdevs tracking the
 *		  state internally). Initialized by calling
 *		  v4l2_subdev_init_finalize().
+ * @enabled_streams: Bitmask of enabled streams used by
+ *		     v4l2_subdev_enable_streams() and
+ *		     v4l2_subdev_disable_streams() helper functions for fallback
+ *		     cases.
 *
 * Each instance of a subdev driver should create this struct, either
 * stand-alone or embedded in a larger struct.
@@ -1050,6 +1074,7 @@ struct v4l2_subdev {
	 * doesn't support it.
	 */
	struct v4l2_subdev_state *active_state;
+	u64 enabled_streams;
};


@@ -1641,6 +1666,66 @@ int v4l2_subdev_routing_validate(struct v4l2_subdev *sd,
				 const struct v4l2_subdev_krouting *routing,
				 enum v4l2_subdev_routing_restriction disallow);

+/**
+ * v4l2_subdev_enable_streams() - Enable streams on a pad
+ * @sd: The subdevice
+ * @pad: The pad
+ * @streams_mask: Bitmask of streams to enable
+ *
+ * This function enables streams on a source @pad of a subdevice. The pad is
+ * identified by its index, while the streams are identified by the
+ * @streams_mask bitmask. This allows enabling multiple streams on a pad at
+ * once.
+ *
+ * Enabling a stream that is already enabled isn't allowed. If @streams_mask
+ * contains an already enabled stream, this function returns -EALREADY without
+ * performing any operation.
+ *
+ * Per-stream enable is only available for subdevs that implement the
+ * .enable_streams() and .disable_streams() operations. For other subdevs, this
+ * function implements a best-effort compatibility by calling the .s_stream()
+ * operation, limited to subdevs that have a single source pad.
+ *
+ * Return:
+ * * 0: Success
+ * * -EALREADY: One of the streams in streams_mask is already enabled
+ * * -EINVAL: The pad index is invalid, or doesn't correspond to a source pad
+ * * -EOPNOTSUPP: Falling back to the legacy .s_stream() operation is
+ *   impossible because the subdev has multiple source pads
+ */
+int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
+			       u64 streams_mask);
+
+/**
+ * v4l2_subdev_disable_streams() - Disable streams on a pad
+ * @sd: The subdevice
+ * @pad: The pad
+ * @streams_mask: Bitmask of streams to disable
+ *
+ * This function disables streams on a source @pad of a subdevice. The pad is
+ * identified by its index, while the streams are identified by the
+ * @streams_mask bitmask. This allows disabling multiple streams on a pad at
+ * once.
+ *
+ * Disabling a streams that is not enabled isn't allowed. If @streams_mask
+ * contains a disabled stream, this function returns -EALREADY without
+ * performing any operation.
+ *
+ * Per-stream disable is only available for subdevs that implement the
+ * .enable_streams() and .disable_streams() operations. For other subdevs, this
+ * function implements a best-effort compatibility by calling the .s_stream()
+ * operation, limited to subdevs that have a single source pad.
+ *
+ * Return:
+ * * 0: Success
+ * * -EALREADY: One of the streams in streams_mask is not enabled
+ * * -EINVAL: The pad index is invalid, or doesn't correspond to a source pad
+ * * -EOPNOTSUPP: Falling back to the legacy .s_stream() operation is
+ *   impossible because the subdev has multiple source pads
+ */
+int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
+				u64 streams_mask);
+
#endif /* CONFIG_VIDEO_V4L2_SUBDEV_API */

#endif /* CONFIG_MEDIA_CONTROLLER */
--
2.34.1




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