On Mon, 16 Jan 2017 16:54:29 -0600 Rob Herring <robh@xxxxxxxxxx> wrote: > From: Alan Cox <alan@xxxxxxxxxxxxxxx> > > Let us create tty objects entirely in kernel space. Untested proposal to > show why all the ideas around rewriting half the uart stack are not needed. > > With this a kernel created non file backed tty object could be used to handle > data, and set terminal modes. Not all ldiscs can cope with this as N_TTY in > particular has to work back to the fs/tty layer. > > The tty_port code is however otherwise clean of file handles as far as I can > tell as is the low level tty port write path used by the ldisc, the > configuration low level interfaces and most of the ldiscs. > > Currently you don't have any exposure to see tty hangups because those are > built around the file layer. However a) it's a fixed port so you probably > don't care about that b) if you do we can add a callback and c) you almost > certainly don't want the userspace tear down/rebuild behaviour anyway. > > This should however be sufficient if we wanted for example to enumerate all > the bluetooth bound fixed ports via ACPI and make them directly available. > It doesn't deal with the case of a user opening a port that's also kernel > opened and that would need some locking out (so it returned EBUSY if bound > to a kernel device of some kind). That needs resolving along with how you > "up" or "down" your new bluetooth device, or enumerate it while providing > the existing tty API to avoid regressions (and to debug). > > Alan > Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > Reviewed-By: Sebastian Reichel <sre@xxxxxxxxxx> > --- > Alan, Need your SoB here. Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxx> Alan -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
