Re: [PATCH v4 5/9] media: v4l: subdev: Make stream argument optional in state access functions

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On Fri, Oct 27, 2023 at 09:06:17AM +0000, Sakari Ailus wrote:
> Hi Laurent,
> 
> On Thu, Oct 26, 2023 at 04:49:04PM +0300, Laurent Pinchart wrote:
> > On Thu, Oct 26, 2023 at 10:03:25AM +0300, Sakari Ailus wrote:
> > > The sub-device state access functions take three arguments: sub-device
> > > state, pad and stream. The stream is not relevant for the majority of
> > > drivers and having to specify 0 for the stream is considered a nuisance.
> > > 
> > > Provide a two-argument macros for these state access functions to cover
> > > the needs of stream-unaware users.
> > > 
> > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > > Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > > ---
> > >  drivers/media/v4l2-core/v4l2-subdev.c | 18 +++++-----
> > >  include/media/v4l2-subdev.h           | 48 ++++++++++++++++++++++-----
> > >  2 files changed, 48 insertions(+), 18 deletions(-)
> > > 
> > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> > > index 2a615836c1d4..9d4ff9b4fcec 100644
> > > --- a/drivers/media/v4l2-core/v4l2-subdev.c
> > > +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> > > @@ -1671,8 +1671,8 @@ int v4l2_subdev_set_routing_with_fmt(struct v4l2_subdev *sd,
> > >  EXPORT_SYMBOL_GPL(v4l2_subdev_set_routing_with_fmt);
> > >  
> > >  struct v4l2_mbus_framefmt *
> > > -v4l2_subdev_state_get_format(struct v4l2_subdev_state *state, unsigned int pad,
> > > -			     u32 stream)
> > > +__v4l2_subdev_state_get_format_stream(struct v4l2_subdev_state *state,
> > > +				      unsigned int pad, u32 stream)
> > >  {
> > >  	struct v4l2_subdev_stream_configs *stream_configs;
> > >  	unsigned int i;
> > > @@ -1706,11 +1706,11 @@ v4l2_subdev_state_get_format(struct v4l2_subdev_state *state, unsigned int pad,
> > >  
> > >  	return NULL;
> > >  }
> > > -EXPORT_SYMBOL_GPL(v4l2_subdev_state_get_format);
> > > +EXPORT_SYMBOL_GPL(__v4l2_subdev_state_get_format_stream);
> > >  
> > >  struct v4l2_rect *
> > > -v4l2_subdev_state_get_crop(struct v4l2_subdev_state *state, unsigned int pad,
> > > -			   u32 stream)
> > > +__v4l2_subdev_state_get_crop_stream(struct v4l2_subdev_state *state,
> > > +				    unsigned int pad, u32 stream)
> > >  {
> > >  	struct v4l2_subdev_stream_configs *stream_configs;
> > >  	unsigned int i;
> > > @@ -1744,11 +1744,11 @@ v4l2_subdev_state_get_crop(struct v4l2_subdev_state *state, unsigned int pad,
> > >  
> > >  	return NULL;
> > >  }
> > > -EXPORT_SYMBOL_GPL(v4l2_subdev_state_get_crop);
> > > +EXPORT_SYMBOL_GPL(__v4l2_subdev_state_get_crop_stream);
> > >  
> > >  struct v4l2_rect *
> > > -v4l2_subdev_state_get_compose(struct v4l2_subdev_state *state, unsigned int pad,
> > > -			      u32 stream)
> > > +__v4l2_subdev_state_get_compose_stream(struct v4l2_subdev_state *state,
> > > +				       unsigned int pad, u32 stream)
> > >  {
> > >  	struct v4l2_subdev_stream_configs *stream_configs;
> > >  	unsigned int i;
> > > @@ -1782,7 +1782,7 @@ v4l2_subdev_state_get_compose(struct v4l2_subdev_state *state, unsigned int pad,
> > >  
> > >  	return NULL;
> > >  }
> > > -EXPORT_SYMBOL_GPL(v4l2_subdev_state_get_compose);
> > > +EXPORT_SYMBOL_GPL(__v4l2_subdev_state_get_compose_stream);
> > >  
> > >  int v4l2_subdev_routing_find_opposite_end(const struct v4l2_subdev_krouting *routing,
> > >  					  u32 pad, u32 stream, u32 *other_pad,
> > > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> > > index 71cb35133b4a..ebb3373b431a 100644
> > > --- a/include/media/v4l2-subdev.h
> > > +++ b/include/media/v4l2-subdev.h
> > > @@ -1545,7 +1545,7 @@ int v4l2_subdev_set_routing_with_fmt(struct v4l2_subdev *sd,
> > >   * v4l2_subdev_state_get_format() - Get pointer to a stream format
> > >   * @state: subdevice state
> > >   * @pad: pad id
> > > - * @stream: stream id
> > > + * @...: stream id (optional argument)
> > >   *
> > >   * This returns a pointer to &struct v4l2_mbus_framefmt for the given pad +
> > >   * stream in the subdev state.
> > > @@ -1553,15 +1553,31 @@ int v4l2_subdev_set_routing_with_fmt(struct v4l2_subdev *sd,
> > >   * For stream-unaware drivers the format for the corresponding pad is returned.
> > >   * If the pad does not exist, NULL is returned.
> > >   */
> > > +/*
> > > + * Wrap v4l2_subdev_state_get_format(), allowing the function to be called with
> > > + * two or three arguments. The purpose of the __v4l2_subdev_state_get_format()
> > > + * macro below is to come up with the name of the function or macro to call,
> > > + * using the last two arguments (_stream and _pad). The selected function or
> > > + * macro is then called using the arguments specified by the caller. A similar
> > > + * arrangement is used for v4l2_subdev_state_crop() and
> > > + * v4l2_subdev_state_compose() below.
> > > + */
> > > +#define v4l2_subdev_state_get_format(...)				\
> > > +	__v4l2_subdev_state_get_format(__VA_ARGS__,			\
> > > +				       _stream, _pad)(__VA_ARGS__)
> > > +#define __v4l2_subdev_state_get_format(_1, _2, _3, ARG, ...)	\
> > 
> > How about renaming this macro to __v4l2_subdev_state_get_format_name ...
> > 
> > > +	__v4l2_subdev_state_get_format ## ARG
> > > +#define __v4l2_subdev_state_get_format_pad(state, pad)		\
> > > +	__v4l2_subdev_state_get_format_stream(state, pad, 0)
> > >  struct v4l2_mbus_framefmt *
> > > -v4l2_subdev_state_get_format(struct v4l2_subdev_state *state, unsigned int pad,
> > > -			     u32 stream);
> > > +__v4l2_subdev_state_get_format_stream(struct v4l2_subdev_state *state,
> > > +				      unsigned int pad, u32 stream);
> > 
> > ... and this function to __v4l2_subdev_state_get_format() ? That way the
> > macro used by drivers and the backend function will have the same name,
> > with a __ prefix for the function. I think it would be a bit cleaner.
> > Same below.
> > 
> > But now that I've written that, I realize you would need an additional
> > __v4l2_subdev_state_get_format_stream() macro. I'll let you decide if
> > you think that's cleaner or not.
> > 
> > 
> > You could also take it one step forward, and avoid three copies of the
> > same name selection macro:
> > 
> > #define __v4l2_subdev_state_get_macro(name, _1, _2, _3, ARG, ...)	\
> > 	__v4l2_subdev_state_get_ ## name ## ARG
> > 
> > #define v4l2_subdev_state_get_format(...)				\
> > 	__v4l2_subdev_state_get_macro(format, __VA_ARGS__,		\
> > 				      _stream, _pad)(__VA_ARGS__)
> 
> This seems like a good idea. How about calling it
> __v4l2_subdev_state_gen_call()? It better describes what it does I think.

Works for me. It's internal anyway.

> > #define __v4l2_subdev_state_get_format_pad(state, pad)			\
> > 	__v4l2_subdev_state_get_format(state, pad, 0)
> > #define __v4l2_subdev_state_get_format_stream(state, pad, stream)	\
> > 	__v4l2_subdev_state_get_format(state, pad, stream)
> 
> This one isn't needed.

You could indeed drop it if you remove the _stream argument to the
__v4l2_subdev_state_get_macro() macro above. I thought it would be nice
to keep it though, to make it more explicit, but I don't mind much.

> > struct v4l2_mbus_framefmt *
> > __v4l2_subdev_state_get_format(struct v4l2_subdev_state *state,
> > 			       unsigned int pad, u32 stream);
> > 
> > This can be done regardless of whether or not we want to drop the
> > _stream suffix from the backend functions.
> > 
> > >  /**
> > >   * v4l2_subdev_state_get_crop() - Get pointer to a stream crop rectangle
> > >   * @state: subdevice state
> > >   * @pad: pad id
> > > - * @stream: stream id
> > > + * @...: stream id (optional argument)
> > >   *
> > >   * This returns a pointer to crop rectangle for the given pad + stream in the
> > >   * subdev state.
> > > @@ -1569,15 +1585,22 @@ v4l2_subdev_state_get_format(struct v4l2_subdev_state *state, unsigned int pad,
> > >   * For stream-unaware drivers the crop rectangle for the corresponding pad is
> > >   * returned. If the pad does not exist, NULL is returned.
> > >   */
> > > +#define v4l2_subdev_state_get_crop(...)					\
> > > +	__v4l2_subdev_state_get_crop(__VA_ARGS__,			\
> > > +				     _stream, _pad)(__VA_ARGS__)
> > > +#define __v4l2_subdev_state_get_crop(_1, _2, _3, ARG, ...)	\
> > > +	__v4l2_subdev_state_get_crop ## ARG
> > > +#define __v4l2_subdev_state_get_crop_pad(state, pad)		\
> > > +	__v4l2_subdev_state_get_crop_stream(state, pad, 0)
> > >  struct v4l2_rect *
> > > -v4l2_subdev_state_get_crop(struct v4l2_subdev_state *state, unsigned int pad,
> > > -			   u32 stream);
> > > +__v4l2_subdev_state_get_crop_stream(struct v4l2_subdev_state *state,
> > > +				    unsigned int pad, u32 stream);
> > >  
> > >  /**
> > >   * v4l2_subdev_state_get_compose() - Get pointer to a stream compose rectangle
> > >   * @state: subdevice state
> > >   * @pad: pad id
> > > - * @stream: stream id
> > > + * @...: stream id (optional argument)
> > >   *
> > >   * This returns a pointer to compose rectangle for the given pad + stream in the
> > >   * subdev state.
> > > @@ -1585,9 +1608,16 @@ v4l2_subdev_state_get_crop(struct v4l2_subdev_state *state, unsigned int pad,
> > >   * For stream-unaware drivers the compose rectangle for the corresponding pad is
> > >   * returned. If the pad does not exist, NULL is returned.
> > >   */
> > > +#define v4l2_subdev_state_get_compose(...)				\
> > > +	__v4l2_subdev_state_get_compose(__VA_ARGS__,		\
> > > +					_stream, _pad)(__VA_ARGS__)
> > > +#define __v4l2_subdev_state_get_compose(_1, _2, _3, ARG, ...)	\
> > > +	__v4l2_subdev_state_get_compose ## ARG
> > > +#define __v4l2_subdev_state_get_compose_pad(state, pad)		\
> > > +	__v4l2_subdev_state_get_compose_stream(state, pad, 0)
> > >  struct v4l2_rect *
> > > -v4l2_subdev_state_get_compose(struct v4l2_subdev_state *state, unsigned int pad,
> > > -			      u32 stream);
> > > +__v4l2_subdev_state_get_compose_stream(struct v4l2_subdev_state *state,
> > > +				       unsigned int pad, u32 stream);
> > >  
> > >  /**
> > >   * v4l2_subdev_routing_find_opposite_end() - Find the opposite stream

-- 
Regards,

Laurent Pinchart



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