| Message ID | CALdTtnvRL-OLGRRWx9-2=9tCGKuyAR+LL=CE5taR-7vebZhAFg@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On Mon, Jun 09, 2014 at 04:57:22PM -0600, Dann Frazier wrote: > Also not in utopic, but utopic should automatically pick it up when we > migrate it to 3.16. > From 667c1c27e4c0b191ec0e210418b45043c68de1ee Mon Sep 17 00:00:00 2001 > From: Murali Karicheri <m-karicheri2@ti.com> > Date: Thu, 1 May 2014 15:04:53 -0400 > Subject: [PATCH] serial: uart: add hw flow control support configuration > > BugLink: https://bugs.launchpad.net/bugs/1328295 > > commit 06aa82e498c144c7784a6f3d3b55458b272d6146 upstream. > > 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@ti.com> > CC: Rob Herring <robh+dt@kernel.org> > CC: Pawel Moll <pawel.moll@arm.com> > CC: Mark Rutland <mark.rutland@arm.com> > CC: Ian Campbell <ijc+devicetree@hellion.org.uk> > CC: Kumar Gala <galak@codeaurora.org> > CC: Randy Dunlap <rdunlap@infradead.org> > CC: Jiri Slaby <jslaby@suse.cz> > CC: Santosh Shilimkar <santosh.shilimkar@ti.com> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Signed-off-by: dann frazier <dann.frazier@canonical.com> > --- > Documentation/devicetree/bindings/serial/of-serial.txt | 1 + > 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, 18 insertions(+), 5 deletions(-) > > diff --git a/Documentation/devicetree/bindings/serial/of-serial.txt b/Documentation/devicetree/bindings/serial/of-serial.txt > index 1928a3e..7705477 100644 > --- a/Documentation/devicetree/bindings/serial/of-serial.txt > +++ b/Documentation/devicetree/bindings/serial/of-serial.txt > @@ -37,6 +37,7 @@ 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. > +- has-hw-flow-control: the hardware has flow control capability. > > Example: > > diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c > index 61ecd70..49fc41ec 100644 > --- a/drivers/tty/serial/8250/8250_core.c > +++ b/drivers/tty/serial/8250/8250_core.c > @@ -2334,9 +2334,11 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, > * the trigger, or the MCR RTS bit is cleared. In the case where > * the remote UART is not using CTS auto flow control, we must > * have sufficient FIFO entries for the latency of the remote > - * UART to respond. IOW, at least 32 bytes of FIFO. > + * UART to respond. IOW, at least 32 bytes of FIFO. Also enable > + * AFE if hw flow control is supported > */ > - if (up->capabilities & UART_CAP_AFE && port->fifosize >= 32) { > + if ((up->capabilities & UART_CAP_AFE && (port->fifosize >= 32)) || > + (port->flags & UPF_HARD_FLOW)) { > up->mcr &= ~UART_MCR_AFE; > if (termios->c_cflag & CRTSCTS) > up->mcr |= UART_MCR_AFE; > diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c > index 2caf9c6..a41d161 100644 > --- a/drivers/tty/serial/of_serial.c > +++ b/drivers/tty/serial/of_serial.c > @@ -183,6 +183,10 @@ static int of_platform_serial_probe(struct platform_device *ofdev) > "auto-flow-control")) > port8250.capabilities |= UART_CAP_AFE; > > + if (of_property_read_bool(ofdev->dev.of_node, > + "has-hw-flow-control")) > + port8250.port.flags |= UPF_HARD_FLOW; > + > ret = serial8250_register_8250_port(&port8250); > break; > } > diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c > index 0f02351..a91af71 100644 > --- a/drivers/tty/serial/serial_core.c > +++ b/drivers/tty/serial/serial_core.c > @@ -170,8 +170,12 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, > if (tty->termios.c_cflag & CBAUD) > uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR); > } > - > - if (tty_port_cts_enabled(port)) { > + /* > + * if hw support flow control without software intervention, > + * then skip the below check > + */ > + if (tty_port_cts_enabled(port) && > + !(uport->flags & UPF_HARD_FLOW)) { > spin_lock_irq(&uport->lock); > if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS)) > tty->hw_stopped = 1; > @@ -2754,7 +2758,9 @@ void uart_handle_cts_change(struct uart_port *uport, unsigned int status) > > uport->icount.cts++; > > - if (tty_port_cts_enabled(port)) { > + /* skip below code if the hw flow control is supported */ > + if (tty_port_cts_enabled(port) && > + !(uport->flags & UPF_HARD_FLOW)) { > if (tty->hw_stopped) { > if (status) { > tty->hw_stopped = 0; > -- > 2.0.0 > Is an upstrea cherry-pick, looks to do what is claimed, is device specific and only triggered by a device tree flag so low regression potential. Therefore: Acked-by: Andy Whitcroft <apw@canonical.com> -apw
On Mon, Jun 09, 2014 at 04:57:22PM -0600, Dann Frazier wrote: > Also not in utopic, but utopic should automatically pick it up when we > migrate it to 3.16. > From 667c1c27e4c0b191ec0e210418b45043c68de1ee Mon Sep 17 00:00:00 2001 > From: Murali Karicheri <m-karicheri2@ti.com> > Date: Thu, 1 May 2014 15:04:53 -0400 > Subject: [PATCH] serial: uart: add hw flow control support configuration > > BugLink: https://bugs.launchpad.net/bugs/1328295 > > commit 06aa82e498c144c7784a6f3d3b55458b272d6146 upstream. it's a clean upstream cherry-pick and it only gets triggered when a new DT attribute is present, thus: Acked-by: Paolo Pisati <paolo.pisati@canonical.com>
From 667c1c27e4c0b191ec0e210418b45043c68de1ee Mon Sep 17 00:00:00 2001 From: Murali Karicheri <m-karicheri2@ti.com> Date: Thu, 1 May 2014 15:04:53 -0400 Subject: [PATCH] serial: uart: add hw flow control support configuration BugLink: https://bugs.launchpad.net/bugs/1328295 commit 06aa82e498c144c7784a6f3d3b55458b272d6146 upstream. 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@ti.com> CC: Rob Herring <robh+dt@kernel.org> CC: Pawel Moll <pawel.moll@arm.com> CC: Mark Rutland <mark.rutland@arm.com> CC: Ian Campbell <ijc+devicetree@hellion.org.uk> CC: Kumar Gala <galak@codeaurora.org> CC: Randy Dunlap <rdunlap@infradead.org> CC: Jiri Slaby <jslaby@suse.cz> CC: Santosh Shilimkar <santosh.shilimkar@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: dann frazier <dann.frazier@canonical.com> --- Documentation/devicetree/bindings/serial/of-serial.txt | 1 + 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, 18 insertions(+), 5 deletions(-) diff --git a/Documentation/devicetree/bindings/serial/of-serial.txt b/Documentation/devicetree/bindings/serial/of-serial.txt index 1928a3e..7705477 100644 --- a/Documentation/devicetree/bindings/serial/of-serial.txt +++ b/Documentation/devicetree/bindings/serial/of-serial.txt @@ -37,6 +37,7 @@ 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. +- has-hw-flow-control: the hardware has flow control capability. Example: diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 61ecd70..49fc41ec 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -2334,9 +2334,11 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, * the trigger, or the MCR RTS bit is cleared. In the case where * the remote UART is not using CTS auto flow control, we must * have sufficient FIFO entries for the latency of the remote - * UART to respond. IOW, at least 32 bytes of FIFO. + * UART to respond. IOW, at least 32 bytes of FIFO. Also enable + * AFE if hw flow control is supported */ - if (up->capabilities & UART_CAP_AFE && port->fifosize >= 32) { + if ((up->capabilities & UART_CAP_AFE && (port->fifosize >= 32)) || + (port->flags & UPF_HARD_FLOW)) { up->mcr &= ~UART_MCR_AFE; if (termios->c_cflag & CRTSCTS) up->mcr |= UART_MCR_AFE; diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c index 2caf9c6..a41d161 100644 --- a/drivers/tty/serial/of_serial.c +++ b/drivers/tty/serial/of_serial.c @@ -183,6 +183,10 @@ static int of_platform_serial_probe(struct platform_device *ofdev) "auto-flow-control")) port8250.capabilities |= UART_CAP_AFE; + if (of_property_read_bool(ofdev->dev.of_node, + "has-hw-flow-control")) + port8250.port.flags |= UPF_HARD_FLOW; + ret = serial8250_register_8250_port(&port8250); break; } diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 0f02351..a91af71 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -170,8 +170,12 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, if (tty->termios.c_cflag & CBAUD) uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR); } - - if (tty_port_cts_enabled(port)) { + /* + * if hw support flow control without software intervention, + * then skip the below check + */ + if (tty_port_cts_enabled(port) && + !(uport->flags & UPF_HARD_FLOW)) { spin_lock_irq(&uport->lock); if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS)) tty->hw_stopped = 1; @@ -2754,7 +2758,9 @@ void uart_handle_cts_change(struct uart_port *uport, unsigned int status) uport->icount.cts++; - if (tty_port_cts_enabled(port)) { + /* skip below code if the hw flow control is supported */ + if (tty_port_cts_enabled(port) && + !(uport->flags & UPF_HARD_FLOW)) { if (tty->hw_stopped) { if (status) { tty->hw_stopped = 0; -- 2.0.0