>-----Original Message----- >From: Mark Rutland [mailto:[email protected]] >Sent: Tuesday, April 29, 2014 6:28 PM >To: Karicheri, Muralidharan >Cc: [email protected]; [email protected]; >[email protected]; >[email protected]; Rob Herring; Ian Campbell; Kumar Gala; Randy >Dunlap; Greg >Kroah-Hartman; Jiri Slaby; Shilimkar, Santosh >Subject: Re: [PATCH v1] serial: uart: add hw flow control support configuration > >Hi, > >On Tue, Apr 29, 2014 at 06:22:02PM +0100, Murali Karicheri wrote: >> 8250 uart driver currently supports only software assisted hw flow >> control. The software assisted hw flow control maintains a hw_stopped >> flag in the tty structure to stop and start transmission and use modem >> status interrupt for the event to drive the handshake signals. This is >> not needed if hw has flow control capabilities. This patch adds a DT >> attribute for enabling hw flow control for a uart port. Also skip stop >> and start if this flag is present in flag field of the port structure. >> >> Signed-off-by: Murali Karicheri <[email protected]> >> >> CC: Rob Herring <[email protected]> >> CC: Pawel Moll <[email protected]> >> CC: Mark Rutland <[email protected]> >> CC: Ian Campbell <[email protected]> >> CC: Kumar Gala <[email protected]> >> CC: Randy Dunlap <[email protected]> >> CC: Greg Kroah-Hartman <[email protected]> >> CC: Jiri Slaby <[email protected]> >> CC: Santosh Shilimkar <[email protected]> >> --- >> - Fixed brackets around port->flags & UPF_HARD_FLOW as per comments >> .../devicetree/bindings/serial/of-serial.txt | 2 ++ >> drivers/tty/serial/8250/8250_core.c | 6 ++++-- >> drivers/tty/serial/of_serial.c | 4 ++++ >> drivers/tty/serial/serial_core.c | 12 +++++++++--- >> 4 files changed, 19 insertions(+), 5 deletions(-) >> >> diff --git a/Documentation/devicetree/bindings/serial/of-serial.txt >> b/Documentation/devicetree/bindings/serial/of-serial.txt >> index 1928a3e..123de01 100644 >> --- a/Documentation/devicetree/bindings/serial/of-serial.txt >> +++ b/Documentation/devicetree/bindings/serial/of-serial.txt >> @@ -37,6 +37,8 @@ Optional properties: >> - auto-flow-control: one way to enable automatic flow control support. The >> driver is allowed to detect support for the capability even without this >> property. >> +- hw-flow-control: this enables pure hw flow control and no software >> + intervention needed. > >From the wording of the commit message, I believe this would be better worded >something like: > >- hw-flow-control: the hardware has flow control capability. > >While the OS needs to know that flow control is present if it wishes to make >use of it, >whether or not the OS does so is not a matter for the binding. > >It might also be better worded as "has-hw-flow-control", which would make that >distinction clearer. > >Otherwise this looks fine to me.
Fine. Will re-send with rewording as has-hw-flow-control: the hardware has flow control capability. Murali > >Thanks, >Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
