Hi, On Thu, Jan 24, 2013 at 07:16:39PM +0100, Michal Nazarewicz wrote: > On Thu, Jan 24 2013, Felipe Balbi wrote: > > Hmm, looks like there's no easy way out. Can we (easily) make > > a compatibility layer between the two ? What are the biggest > > differences? > > The biggest difference is that gadgetfs application handles all setup > requests whereas with functionfs most of them are handled by composite > layer. One of the consequence is that functionfs applications have to > provide all the descriptors and strings up front, whereas gadgetfs > applications only need to handle setup requests. > > A compatibility layer would have to send fake requests to gadgetfs > application to get all that information and once received register with > composite framework. > > This could even provide all the functionality as long as we ignore any > unhealthy cases where a gadgetfs application replies to the same setup > request differently depending on some internal state (dunno how > conferment such behaviour would be with USB spec). > > However, I feel it's a lot of work with little (if any) benefit and > that's why I didn't do that in the first place when functionfs was > created. the benefit is that we will be able to go ahed with configfs-based binding and will be able to drop duplicated gadget code between legacy (non-composite) and composite framework with the function drivers. -- balbi
Attachment:
signature.asc
Description: Digital signature
