Re: [PATCH v11 35/36] media: v4l2-subdev: Add subdev .(enable|disable)_streams() operations

[Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>]

On 16/03/2022 14:05, Jacopo Mondi wrote:
> Hi Tomi,
> 
> On Tue, Mar 01, 2022 at 06:11:55PM +0200, Tomi Valkeinen wrote:
>> From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>>
>> 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.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>> ---
>>   drivers/media/v4l2-core/v4l2-subdev.c | 216 ++++++++++++++++++++++++++
>>   include/media/v4l2-subdev.h           |  85 ++++++++++
>>   2 files changed, 301 insertions(+)
>>
>> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
>> index 6a9fc62dacbf..f75a1995a70b 100644
>> --- a/drivers/media/v4l2-core/v4l2-subdev.c
>> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
>> @@ -1698,6 +1698,222 @@ __v4l2_subdev_next_active_route(const struct v4l2_subdev_krouting *routing,
>>   }
>>   EXPORT_SYMBOL_GPL(__v4l2_subdev_next_active_route);
>>
>> +static int v4l2_subdev_enable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
>> +					       u64 streams_mask)
>> +{
>> +	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)
>> +		return -EALREADY;
> 
> I wonder if a few dev_dbg on errors might save someone an headache

Yep, I'll add a few.

>> +
>> +	/* 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;
> 
> Should we make sure pad is a SOURCE (and remove the same check in the
> _fallback version) ?

I tried that, but according to Laurent: no. Enable streams may work on 
both directions, i.e. for output drivers it is called on a sink pad.

>> +
>> +	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(cfg->stream)))
>> +			continue;
>> +
>> +		found_streams |= BIT(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",
> 
> nit: I would use the more usual form of entity:pad in the error
> message

Ok.

> I like the idea :)
> 
> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
> 
> Thanks
>    j
> 
>> +			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(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)
>> +{
>> +	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)
>> +		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(cfg->stream)))
>> +			continue;
>> +
>> +		found_streams |= BIT(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(cfg->stream)))
>> +			cfg->enabled = false;
>> +	}
>> +
>> +done:
>> +	v4l2_subdev_unlock_state(state);
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(v4l2_subdev_disable_streams);
>> +
>>   #endif /* CONFIG_MEDIA_CONTROLLER */
>>
>>   void v4l2_subdev_init(struct v4l2_subdev *sd, const struct v4l2_subdev_ops *ops)
>> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
>> index 992debe116ac..bb1713863973 100644
>> --- a/include/media/v4l2-subdev.h
>> +++ b/include/media/v4l2-subdev.h
>> @@ -702,6 +702,7 @@ 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
>> @@ -711,6 +712,7 @@ 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;
>> @@ -816,6 +818,18 @@ 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,
>> @@ -862,6 +876,12 @@ 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);
>>   };
>>
>>   /**
>> @@ -1007,6 +1027,10 @@ 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.
>> @@ -1052,6 +1076,7 @@ struct v4l2_subdev {
>>   	 * doesn't support it.
>>   	 */
>>   	struct v4l2_subdev_state *active_state;
>> +	u64 enabled_streams;
>>   };
>>
>>
>> @@ -1589,6 +1614,66 @@ __v4l2_subdev_next_active_route(const struct v4l2_subdev_krouting *routing,
>>   	for ((route) = NULL;                  \
>>   	     ((route) = __v4l2_subdev_next_active_route((routing), (route)));)
>>
>> +/**
>> + * 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_MEDIA_CONTROLLER */
>>
>>   /**
>> --
>> 2.25.1
>>