Commits
Robert Baldyga committed 18d6b32fca3
usb: gadget: f_fs: add "no_disconnect" mode 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. Tested-by: David Cohen <david.a.cohen@linux.intel.com> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Robert Baldyga <r.baldyga@samsung.com> Signed-off-by: Felipe Balbi <balbi@ti.com>