On Thu, Jan 19, 2017 at 7:37 AM, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > On Mon, Jan 16, 2017 at 04:54:29PM -0600, Rob Herring 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. > > Rob, as this patch is flowing through you, I need your signed-off-by as > well if I am to take it. Right. I've added both for the next version. Rob -- 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
