On Thu, Dec 18, 2014 at 09:55:10AM +0100, Robert Baldyga wrote: > Since we can compose gadgets from many functions, there is the problem > related to gadget breakage while FunctionFS daemon being closed. FFS > function is userspace code so there is no way to know when it will close > files (it doesn't matter what is the reason of this situation, it can > be daemon logic, program breakage, process kill or any other). So when > we have another function in gadget which, for example, sends some amount > of data, does some software update or implements some real-time functionality, > we may want to keep the gadget connected despite FFS function is no longer > functional. > > We can't just remove one of functions from gadget since it has been > enumerated, so the only way to keep entire gadget working is to make > broken FFS function deactivated but still visible to host. For this > purpose this patch introduces "no_disconnect" mode. It can be enabled > by setting mount option "no_disconnect=1", and results with defering > function disconnect to the moment of reopen ep0 file or filesystem > unmount. After closing all endpoint files, FunctionFS is set to state > FFS_DEACTIVATED. > > When ffs->state == FFS_DEACTIVATED: > - function is still bound and visible to host, > - setup requests are automatically stalled, > - transfers on other endpoints are refused, > - epfiles, except ep0, are deleted from the filesystem, > - opening ep0 causes the function to be closed, and then FunctionFS > is ready for descriptors and string write, > - altsetting change causes the function to be closed - we want to keep > function alive until another functions are potentialy used, altsetting > change means that another configuration is being selected or USB cable > was unplugged, which indicates that we don't need to stay longer in > FFS_DEACTIVATED state > - unmounting of the FunctionFS instance causes the function to be closed. > > Signed-off-by: Robert Baldyga <r.baldyga@xxxxxxxxxxx> David, can you test it with your setup ? cheers -- balbi
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