On Thu, Jan 19, 2017 at 9:05 AM, Rob Herring <robh@xxxxxxxxxx> wrote: > 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. Oh, I see you applied the 1st patch. Thanks. If you want to apply this one now here's my S-o-B: Signed-off-by: Rob Herring <robh@xxxxxxxxxx> Patches 3 and 4 can be applied too. For patch 5, I'd really like someone with more tty knowledge to comment on. 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
