On Wed, 29 Jun 2011, Sakari Ailus wrote: > Guennadi Liakhovetski wrote: > > On Mon, 27 Jun 2011, Guennadi Liakhovetski wrote: > > > > [snip] > > > >>> If the structures are expected to be generic I somehow feel that a field of > >>> flags isn't the best way to describe the configuration of CSI-2 or other > >>> busses. Why not to just use a structure with bus type and an union for > >>> bus-specific configuration parameters? It'd be easier to access and also to > >>> change as needed than flags in an unsigned long field. > >> > >> Well, yes, a union can be a good idea, thanks. > > > > ...on a second thought, we currently only have one field: flags, and it is > > common for all 3 bus types: parallel, reduced parallel (bt.656, etc.), and > > CSI-2. In the future, when we need more parameters for any of these busses > > we'll just add such a union, shouldn't be a problem. > > What I meant above was that I would prefer to describe the capabilities > in a structure which would contain appropriate data type for the field, > not as flags or sets of flags in a bit field. > > This would allow e.g. just testing for > v4l2_mbus_config.u.parallel.hsync_active_low instead of > v4l2_mbus_config.flags & V4L2_MBUS_HSYNC_ACTIVE_LOW. This way the flags > used for the bus also express the bus explicitly rather than implicitly. I don't think, using flags is any less explicit, than using struct members. As I already explained, I'd like to use the same interface for querying capabilities, the present configuration, and setting a configuration. This is easily achieved with flags. See the v4l2_mbus_config_compatible() function and try to rewrite all the bitwise operations in it, using your struct. Thanks Guennadi > > Do you see downsides with this compared to using an integer field as > flags? The other benefits of this are described in my earlier comment. > > Regards, > > -- > Sakari Ailus > sakari.ailus@xxxxxx > --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
