On Sun, 26 Apr 2020, Vladimir Stankovic wrote: > On 26.4.20. 02:32, Alan Stern wrote: > > On Sat, 25 Apr 2020 vladimir.stankovic@xxxxxxxxxxxxxxx wrote: > > > >> Protocol adaptation layer (PAL) implementation has been added to > >> introduce MA-USB structures and logic. > >> > >> Signed-off-by: Vladimir Stankovic <vladimir.stankovic@xxxxxxxxxxxxxxx> > > > > ... > > > >> + /* > >> + * Masking URB_SHORT_NOT_OK flag as SCSI driver is adding it where it > >> + * should not, so it is breaking the USB drive on the linux > >> + */ > >> + urb->transfer_flags &= ~URB_SHORT_NOT_OK; > > > > Removing the SHORT_NOT_OK flag is _not_ a valid thing to do. It will > > cause drivers to malfunction. > > > > Can you please explain this comment? > > > > What SCSI driver? > > > > When is the flag being added? > > > > How does it break USB drives? > > > > Why haven't you already reported this problem to the > > appropriate maintainers? > > > > Alan Stern > > > > Hi, > > Issue that removal of SHORT_NOT_OK flag addressed is linked to particular > set of Kingston USB 3.0 flash drives (super speed) - other USB flash drives > haven't had this flag set. Without this "fix", those Kingston flash drives > are not being enumerated properly. Please explain in detail how the enumeration of these Kingston flash drives fails. Or if such an explanation has already been posted, please provide a link to it. > This particular line was added in the early stage of development, during > enumeration process implementation. The reason why it remained in the code > since is because we haven't noticed any side-effects, even with various > USB devices being attached to remote MA-USB device, including flash drives, > cameras, wireless mice, etc. Come to think of it, the SHORT_NOT_OK flag is mainly used with HCDs that don't have scatter-gather support. Since your mausb driver does support scatter-gather, you most likely won't encounter any problems unless you go looking for them specifically. > The problem has been reported, and is actively being investigated. Where was the problem reported (URL to a mailing list archive)? Who is investigating it? > As soon as it gets addressed properly (w/o global negation of the flag), > a new patch will be pushed. Thank you. Alan Stern
