>-----Original Message----- >From: Mark Rutland [mailto:mark.rutland@xxxxxxx] >Sent: Tuesday, April 29, 2014 6:28 PM >To: Karicheri, Muralidharan >Cc: linux-doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-serial@xxxxxxxxxxxxxxx; >devicetree@xxxxxxxxxxxxxxx; 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 <m-karicheri2@xxxxxx> >> >> CC: Rob Herring <robh+dt@xxxxxxxxxx> >> CC: Pawel Moll <pawel.moll@xxxxxxx> >> CC: Mark Rutland <mark.rutland@xxxxxxx> >> CC: Ian Campbell <ijc+devicetree@xxxxxxxxxxxxxx> >> CC: Kumar Gala <galak@xxxxxxxxxxxxxx> >> CC: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> >> CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> >> CC: Jiri Slaby <jslaby@xxxxxxx> >> CC: Santosh Shilimkar <santosh.shilimkar@xxxxxx> >> --- >> - 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 devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
