On 02/12/14 13:11, Ricardo Ribalda Delgado wrote: > Hi Hans > > Thanks for your reply > > On Wed, Feb 12, 2014 at 12:20 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote: >> Hi Ricardo, >> >> On 02/12/14 11:44, Ricardo Ribalda Delgado wrote: >>> Hello Hans >>> >>> In the case of U8 and U16 data types. Why dont you fill the elem_size >>> automatically in v4l2_ctrl and request the driver to fill the field? >> >> When you create the control the control framework has to know the element >> size beforehand as it will use that to allocate the memory containing the >> control's value. The control framework is aware of the 'old' control types >> and will fill in the elem_size accordingly, but it cannot do that in the >> general case for these complex types. I guess it could be filled in by the >> framework for the more common types (U8, U16) but I felt it was more >> consistent to just require drivers to fill it in manually, rather than have >> it set for some types but not for others. >> >>> >>> Other option would be not declaring the basic data types (U8, U16, >>> U32...) and use elem_size. Ie. If type==V4L2_CTRL_COMPLEX_TYPES, then >>> the type is basic and elem_size is the size of the type. If the type >>>> V4L2_CTRL_COMPLEX_TYPES the type is not basic. >> >> You still need to know the type. Applications have to be able to check for >> the type, the element size by itself doesn't tell you how to interpret the >> data, you need the type identifier as well. > > I think that the driver is setting twice the same info. I see no gain > in declaring U8, U16 types etc if we still have to set the element > size. This is why I believe that we should only declare the "structs". Just to make sure I understand you: for simple types like U8/U16 you want the control framework to fill in elem_size, for more complex types (structs) you want the driver to fill in elem_size? > what about something like: V4L2_CTRL_COMPLEX_TYPE_SIGNED_INTEGER + > size, V4L2_CTRL_COMPLEX_TYPES_UNSIGNED_INTEGER + size.... instead of > V4L2_CTRL_COMPLEX_TYPES_U8, V4L2_CTRL_COMPLEX_TYPES_U16, > V4L2_CTRL_COMPLEX_TYPES_U32, V4L2_CTRL_COMPLEX_TYPES_S8 .... > > Btw, I am trying to implement a dead pixel control on the top of you > api. Shall I wait until you patchset is merged or shall I send the > patches right away? You're free to experiment, but I am not going to ask Mauro to pull additional patches as long as this initial patch set isn't merged. Regards, Hans -- 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
