| Message ID | 1404928177-26554-4-git-send-email-bigeasy@linutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
* Sebastian Andrzej Siewior <bigeasy@linutronix.de> [140709 10:52]: > While comparing the OMAP-serial and the 8250 part of this I noticed that > the the latter does not use runtime-pm. Here are the pieces. It is > basically a get before first register access and a last_busy + put after > last access. > If I understand this correct, it should do nothing as long as > pm_runtime_use_autosuspend() + pm_runtime_enable() isn't invoked on the > device. ... > --- a/drivers/tty/serial/8250/8250_core.c > +++ b/drivers/tty/serial/8250/8250_core.c > @@ -571,7 +573,17 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep) > serial_out(p, UART_EFR, 0); > serial_out(p, UART_LCR, 0); > } > + > + if (!device_may_wakeup(p->port.dev)) { > + if (sleep) > + pm_runtime_forbid(p->port.dev); > + else > + pm_runtime_allow(p->port.dev); > + } > } > +out: > + pm_runtime_mark_last_busy(p->port.dev); > + pm_runtime_put_autosuspend(p->port.dev); > } The device_may_wakeup logic here is wrong as I described in the earlier thread. For runtime PM, the wake-up events should be always enabled. So the device_may_wakeup checks should be only done for suspend and resume. Regards, Tony
On 07/10/2014 08:28 AM, Tony Lindgren wrote: >> --- a/drivers/tty/serial/8250/8250_core.c >> +++ b/drivers/tty/serial/8250/8250_core.c >> @@ -571,7 +573,17 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep) >> serial_out(p, UART_EFR, 0); >> serial_out(p, UART_LCR, 0); >> } >> + >> + if (!device_may_wakeup(p->port.dev)) { >> + if (sleep) >> + pm_runtime_forbid(p->port.dev); >> + else >> + pm_runtime_allow(p->port.dev); >> + } >> } >> +out: >> + pm_runtime_mark_last_busy(p->port.dev); >> + pm_runtime_put_autosuspend(p->port.dev); >> } > > The device_may_wakeup logic here is wrong as I described in the > earlier thread. For runtime PM, the wake-up events should be > always enabled. So the device_may_wakeup checks should be only > done for suspend and resume. Okay. I dropped it from here. > > Regards, > > Tony > Sebastian
On Wed, Jul 09, 2014 at 07:49:34PM +0200, Sebastian Andrzej Siewior wrote: > While comparing the OMAP-serial and the 8250 part of this I noticed that > the the latter does not use runtime-pm. Here are the pieces. It is > basically a get before first register access and a last_busy + put after > last access. > If I understand this correct, it should do nothing as long as > pm_runtime_use_autosuspend() + pm_runtime_enable() isn't invoked on the > device. > > Cc: mika.westerberg@linux.intel.com Sorry for the delay, just came back from vacation. Adding Heikki, who knows the 8250_dw driver much better than me. Unfortunately he is still on vacation for next two weeks. > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > drivers/tty/serial/8250/8250_core.c | 101 +++++++++++++++++++++++++++++++----- > 1 file changed, 88 insertions(+), 13 deletions(-) > > diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c > index d37eb08..1a91a89 100644 > --- a/drivers/tty/serial/8250/8250_core.c > +++ b/drivers/tty/serial/8250/8250_core.c > @@ -38,6 +38,7 @@ > #include <linux/nmi.h> > #include <linux/mutex.h> > #include <linux/slab.h> > +#include <linux/pm_runtime.h> > #ifdef CONFIG_SPARC > #include <linux/sunserialcore.h> > #endif > @@ -553,10 +554,11 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep) > * offset but the UART channel may only write to the corresponding > * bit. > */ > + pm_runtime_get_sync(p->port.dev); > if ((p->port.type == PORT_XR17V35X) || > (p->port.type == PORT_XR17D15X)) { > serial_out(p, UART_EXAR_SLEEP, sleep ? 0xff : 0); > - return; > + goto out; > } > > if (p->capabilities & UART_CAP_SLEEP) { > @@ -571,7 +573,17 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep) > serial_out(p, UART_EFR, 0); > serial_out(p, UART_LCR, 0); > } > + > + if (!device_may_wakeup(p->port.dev)) { > + if (sleep) > + pm_runtime_forbid(p->port.dev); > + else > + pm_runtime_allow(p->port.dev); > + } > } > +out: > + pm_runtime_mark_last_busy(p->port.dev); > + pm_runtime_put_autosuspend(p->port.dev); > } > > #ifdef CONFIG_SERIAL_8250_RSA > @@ -1280,6 +1292,7 @@ static void serial8250_stop_tx(struct uart_port *port) > struct uart_8250_port *up = > container_of(port, struct uart_8250_port, port); > > + pm_runtime_get_sync(port->dev); > __stop_tx(up); > > /* > @@ -1289,6 +1302,8 @@ static void serial8250_stop_tx(struct uart_port *port) > up->acr |= UART_ACR_TXDIS; > serial_icr_write(up, UART_ACR, up->acr); > } > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > } > > static void serial8250_start_tx(struct uart_port *port) > @@ -1296,8 +1311,9 @@ static void serial8250_start_tx(struct uart_port *port) > struct uart_8250_port *up = > container_of(port, struct uart_8250_port, port); > > + pm_runtime_get_sync(port->dev); > if (up->dma && !serial8250_tx_dma(up)) { > - return; > + goto out; > } else if (!(up->ier & UART_IER_THRI)) { > up->ier |= UART_IER_THRI; > serial_port_out(port, UART_IER, up->ier); > @@ -1318,6 +1334,9 @@ static void serial8250_start_tx(struct uart_port *port) > up->acr &= ~UART_ACR_TXDIS; > serial_icr_write(up, UART_ACR, up->acr); > } > +out: > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > } > > static void serial8250_stop_rx(struct uart_port *port) > @@ -1325,9 +1344,14 @@ static void serial8250_stop_rx(struct uart_port *port) > struct uart_8250_port *up = > container_of(port, struct uart_8250_port, port); > > + pm_runtime_get_sync(port->dev); > + > up->ier &= ~UART_IER_RLSI; > up->port.read_status_mask &= ~UART_LSR_DR; > serial_port_out(port, UART_IER, up->ier); > + > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > } > > static void serial8250_enable_ms(struct uart_port *port) > @@ -1340,7 +1364,10 @@ static void serial8250_enable_ms(struct uart_port *port) > return; > > up->ier |= UART_IER_MSI; > + pm_runtime_get_sync(port->dev); > serial_port_out(port, UART_IER, up->ier); > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > } > > /* > @@ -1530,9 +1557,17 @@ EXPORT_SYMBOL_GPL(serial8250_handle_irq); > > static int serial8250_default_handle_irq(struct uart_port *port) > { > - unsigned int iir = serial_port_in(port, UART_IIR); > + unsigned int iir; > + int ret; > > - return serial8250_handle_irq(port, iir); > + pm_runtime_get_sync(port->dev); Is this function executed in interrupt context? Calling _sync() variant might sleep here. At least if the RTPM of the device is backed by ACPI methods. > + > + iir = serial_port_in(port, UART_IIR); > + ret = serial8250_handle_irq(port, iir); > + > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > + return ret; > } > > /* > @@ -1790,11 +1825,16 @@ static unsigned int serial8250_tx_empty(struct uart_port *port) > unsigned long flags; > unsigned int lsr; > > + pm_runtime_get_sync(port->dev); > + > spin_lock_irqsave(&port->lock, flags); > lsr = serial_port_in(port, UART_LSR); > up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; > spin_unlock_irqrestore(&port->lock, flags); > > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > + > return (lsr & BOTH_EMPTY) == BOTH_EMPTY ? TIOCSER_TEMT : 0; > } > > @@ -1805,7 +1845,10 @@ static unsigned int serial8250_get_mctrl(struct uart_port *port) > unsigned int status; > unsigned int ret; > > + pm_runtime_get_sync(port->dev); > status = serial8250_modem_status(up); > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > > ret = 0; > if (status & UART_MSR_DCD) > @@ -1838,7 +1881,10 @@ static void serial8250_set_mctrl(struct uart_port *port, unsigned int mctrl) > > mcr = (mcr & up->mcr_mask) | up->mcr_force | up->mcr; > > + pm_runtime_get_sync(port->dev); > serial_port_out(port, UART_MCR, mcr); > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > } > > static void serial8250_break_ctl(struct uart_port *port, int break_state) > @@ -1847,6 +1893,7 @@ static void serial8250_break_ctl(struct uart_port *port, int break_state) > container_of(port, struct uart_8250_port, port); > unsigned long flags; > > + pm_runtime_get_sync(port->dev); > spin_lock_irqsave(&port->lock, flags); > if (break_state == -1) > up->lcr |= UART_LCR_SBC; > @@ -1854,6 +1901,8 @@ static void serial8250_break_ctl(struct uart_port *port, int break_state) > up->lcr &= ~UART_LCR_SBC; > serial_port_out(port, UART_LCR, up->lcr); > spin_unlock_irqrestore(&port->lock, flags); > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > } > > /* > @@ -1898,12 +1947,23 @@ static void wait_for_xmitr(struct uart_8250_port *up, int bits) > > static int serial8250_get_poll_char(struct uart_port *port) > { > - unsigned char lsr = serial_port_in(port, UART_LSR); > + unsigned char lsr; > + int status; > + > + pm_runtime_get_sync(port->dev); > > - if (!(lsr & UART_LSR_DR)) > - return NO_POLL_CHAR; > + lsr = serial_port_in(port, UART_LSR); > > - return serial_port_in(port, UART_RX); > + if (!(lsr & UART_LSR_DR)) { > + status = NO_POLL_CHAR; > + goto out; > + } > + > + status = serial_port_in(port, UART_RX); > +out: > + pm_runtime_mark_last_busy(up->dev); > + pm_runtime_put_autosuspend(up->dev); > + return status; > } > > > @@ -1914,6 +1974,7 @@ static void serial8250_put_poll_char(struct uart_port *port, > struct uart_8250_port *up = > container_of(port, struct uart_8250_port, port); > > + pm_runtime_get_sync(up->dev); > /* > * First save the IER then disable the interrupts > */ > @@ -1935,6 +1996,9 @@ static void serial8250_put_poll_char(struct uart_port *port, > */ > wait_for_xmitr(up, BOTH_EMPTY); > serial_port_out(port, UART_IER, ier); > + pm_runtime_mark_last_busy(up->dev); > + pm_runtime_put_autosuspend(up->dev); > + > } > > #endif /* CONFIG_CONSOLE_POLL */ > @@ -1961,6 +2025,7 @@ int serial8250_do_startup(struct uart_port *port) > if (port->iotype != up->cur_iotype) > set_io_from_upio(port); > > + pm_runtime_get_sync(port->dev); > if (port->type == PORT_16C950) { > /* Wake up and initialize UART */ > up->acr = 0; > @@ -1981,7 +2046,6 @@ int serial8250_do_startup(struct uart_port *port) > */ > enable_rsa(up); > #endif > - > /* > * Clear the FIFO buffers and disable them. > * (they will be reenabled in set_termios()) > @@ -2005,7 +2069,8 @@ int serial8250_do_startup(struct uart_port *port) > (serial_port_in(port, UART_LSR) == 0xff)) { > printk_ratelimited(KERN_INFO "ttyS%d: LSR safety check engaged!\n", > serial_index(port)); > - return -ENODEV; > + retval = -ENODEV; > + goto out; > } > > /* > @@ -2090,7 +2155,7 @@ int serial8250_do_startup(struct uart_port *port) > } else { > retval = serial_link_irq_chain(up); > if (retval) > - return retval; > + goto out; > } > > /* > @@ -2188,8 +2253,11 @@ int serial8250_do_startup(struct uart_port *port) > outb_p(0x80, icp); > inb_p(icp); > } > - > - return 0; > + retval = 0; > +out: > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > + return retval; > } > EXPORT_SYMBOL_GPL(serial8250_do_startup); > > @@ -2207,6 +2275,7 @@ void serial8250_do_shutdown(struct uart_port *port) > container_of(port, struct uart_8250_port, port); > unsigned long flags; > > + pm_runtime_get_sync(port->dev); > /* > * Disable interrupts from this port > */ > @@ -2246,6 +2315,8 @@ void serial8250_do_shutdown(struct uart_port *port) > * the IRQ chain. > */ > serial_port_in(port, UART_RX); > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > > del_timer_sync(&up->timer); > up->timer.function = serial8250_timeout; > @@ -2365,6 +2436,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, > * Ok, we're now changing the port state. Do it with > * interrupts disabled. > */ > + pm_runtime_get_sync(port->dev); > spin_lock_irqsave(&port->lock, flags); > > /* > @@ -2486,6 +2558,9 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, > } > serial8250_set_mctrl(port, port->mctrl); > spin_unlock_irqrestore(&port->lock, flags); > + pm_runtime_mark_last_busy(port->dev); > + pm_runtime_put_autosuspend(port->dev); > + > /* Don't rewrite B0 */ > if (tty_termios_baud_rate(termios)) > tty_termios_encode_baud_rate(termios, baud, baud); > -- > 2.0.1
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index d37eb08..1a91a89 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -38,6 +38,7 @@ #include <linux/nmi.h> #include <linux/mutex.h> #include <linux/slab.h> +#include <linux/pm_runtime.h> #ifdef CONFIG_SPARC #include <linux/sunserialcore.h> #endif @@ -553,10 +554,11 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep) * offset but the UART channel may only write to the corresponding * bit. */ + pm_runtime_get_sync(p->port.dev); if ((p->port.type == PORT_XR17V35X) || (p->port.type == PORT_XR17D15X)) { serial_out(p, UART_EXAR_SLEEP, sleep ? 0xff : 0); - return; + goto out; } if (p->capabilities & UART_CAP_SLEEP) { @@ -571,7 +573,17 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep) serial_out(p, UART_EFR, 0); serial_out(p, UART_LCR, 0); } + + if (!device_may_wakeup(p->port.dev)) { + if (sleep) + pm_runtime_forbid(p->port.dev); + else + pm_runtime_allow(p->port.dev); + } } +out: + pm_runtime_mark_last_busy(p->port.dev); + pm_runtime_put_autosuspend(p->port.dev); } #ifdef CONFIG_SERIAL_8250_RSA @@ -1280,6 +1292,7 @@ static void serial8250_stop_tx(struct uart_port *port) struct uart_8250_port *up = container_of(port, struct uart_8250_port, port); + pm_runtime_get_sync(port->dev); __stop_tx(up); /* @@ -1289,6 +1302,8 @@ static void serial8250_stop_tx(struct uart_port *port) up->acr |= UART_ACR_TXDIS; serial_icr_write(up, UART_ACR, up->acr); } + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); } static void serial8250_start_tx(struct uart_port *port) @@ -1296,8 +1311,9 @@ static void serial8250_start_tx(struct uart_port *port) struct uart_8250_port *up = container_of(port, struct uart_8250_port, port); + pm_runtime_get_sync(port->dev); if (up->dma && !serial8250_tx_dma(up)) { - return; + goto out; } else if (!(up->ier & UART_IER_THRI)) { up->ier |= UART_IER_THRI; serial_port_out(port, UART_IER, up->ier); @@ -1318,6 +1334,9 @@ static void serial8250_start_tx(struct uart_port *port) up->acr &= ~UART_ACR_TXDIS; serial_icr_write(up, UART_ACR, up->acr); } +out: + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); } static void serial8250_stop_rx(struct uart_port *port) @@ -1325,9 +1344,14 @@ static void serial8250_stop_rx(struct uart_port *port) struct uart_8250_port *up = container_of(port, struct uart_8250_port, port); + pm_runtime_get_sync(port->dev); + up->ier &= ~UART_IER_RLSI; up->port.read_status_mask &= ~UART_LSR_DR; serial_port_out(port, UART_IER, up->ier); + + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); } static void serial8250_enable_ms(struct uart_port *port) @@ -1340,7 +1364,10 @@ static void serial8250_enable_ms(struct uart_port *port) return; up->ier |= UART_IER_MSI; + pm_runtime_get_sync(port->dev); serial_port_out(port, UART_IER, up->ier); + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); } /* @@ -1530,9 +1557,17 @@ EXPORT_SYMBOL_GPL(serial8250_handle_irq); static int serial8250_default_handle_irq(struct uart_port *port) { - unsigned int iir = serial_port_in(port, UART_IIR); + unsigned int iir; + int ret; - return serial8250_handle_irq(port, iir); + pm_runtime_get_sync(port->dev); + + iir = serial_port_in(port, UART_IIR); + ret = serial8250_handle_irq(port, iir); + + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); + return ret; } /* @@ -1790,11 +1825,16 @@ static unsigned int serial8250_tx_empty(struct uart_port *port) unsigned long flags; unsigned int lsr; + pm_runtime_get_sync(port->dev); + spin_lock_irqsave(&port->lock, flags); lsr = serial_port_in(port, UART_LSR); up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; spin_unlock_irqrestore(&port->lock, flags); + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); + return (lsr & BOTH_EMPTY) == BOTH_EMPTY ? TIOCSER_TEMT : 0; } @@ -1805,7 +1845,10 @@ static unsigned int serial8250_get_mctrl(struct uart_port *port) unsigned int status; unsigned int ret; + pm_runtime_get_sync(port->dev); status = serial8250_modem_status(up); + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); ret = 0; if (status & UART_MSR_DCD) @@ -1838,7 +1881,10 @@ static void serial8250_set_mctrl(struct uart_port *port, unsigned int mctrl) mcr = (mcr & up->mcr_mask) | up->mcr_force | up->mcr; + pm_runtime_get_sync(port->dev); serial_port_out(port, UART_MCR, mcr); + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); } static void serial8250_break_ctl(struct uart_port *port, int break_state) @@ -1847,6 +1893,7 @@ static void serial8250_break_ctl(struct uart_port *port, int break_state) container_of(port, struct uart_8250_port, port); unsigned long flags; + pm_runtime_get_sync(port->dev); spin_lock_irqsave(&port->lock, flags); if (break_state == -1) up->lcr |= UART_LCR_SBC; @@ -1854,6 +1901,8 @@ static void serial8250_break_ctl(struct uart_port *port, int break_state) up->lcr &= ~UART_LCR_SBC; serial_port_out(port, UART_LCR, up->lcr); spin_unlock_irqrestore(&port->lock, flags); + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); } /* @@ -1898,12 +1947,23 @@ static void wait_for_xmitr(struct uart_8250_port *up, int bits) static int serial8250_get_poll_char(struct uart_port *port) { - unsigned char lsr = serial_port_in(port, UART_LSR); + unsigned char lsr; + int status; + + pm_runtime_get_sync(port->dev); - if (!(lsr & UART_LSR_DR)) - return NO_POLL_CHAR; + lsr = serial_port_in(port, UART_LSR); - return serial_port_in(port, UART_RX); + if (!(lsr & UART_LSR_DR)) { + status = NO_POLL_CHAR; + goto out; + } + + status = serial_port_in(port, UART_RX); +out: + pm_runtime_mark_last_busy(up->dev); + pm_runtime_put_autosuspend(up->dev); + return status; } @@ -1914,6 +1974,7 @@ static void serial8250_put_poll_char(struct uart_port *port, struct uart_8250_port *up = container_of(port, struct uart_8250_port, port); + pm_runtime_get_sync(up->dev); /* * First save the IER then disable the interrupts */ @@ -1935,6 +1996,9 @@ static void serial8250_put_poll_char(struct uart_port *port, */ wait_for_xmitr(up, BOTH_EMPTY); serial_port_out(port, UART_IER, ier); + pm_runtime_mark_last_busy(up->dev); + pm_runtime_put_autosuspend(up->dev); + } #endif /* CONFIG_CONSOLE_POLL */ @@ -1961,6 +2025,7 @@ int serial8250_do_startup(struct uart_port *port) if (port->iotype != up->cur_iotype) set_io_from_upio(port); + pm_runtime_get_sync(port->dev); if (port->type == PORT_16C950) { /* Wake up and initialize UART */ up->acr = 0; @@ -1981,7 +2046,6 @@ int serial8250_do_startup(struct uart_port *port) */ enable_rsa(up); #endif - /* * Clear the FIFO buffers and disable them. * (they will be reenabled in set_termios()) @@ -2005,7 +2069,8 @@ int serial8250_do_startup(struct uart_port *port) (serial_port_in(port, UART_LSR) == 0xff)) { printk_ratelimited(KERN_INFO "ttyS%d: LSR safety check engaged!\n", serial_index(port)); - return -ENODEV; + retval = -ENODEV; + goto out; } /* @@ -2090,7 +2155,7 @@ int serial8250_do_startup(struct uart_port *port) } else { retval = serial_link_irq_chain(up); if (retval) - return retval; + goto out; } /* @@ -2188,8 +2253,11 @@ int serial8250_do_startup(struct uart_port *port) outb_p(0x80, icp); inb_p(icp); } - - return 0; + retval = 0; +out: + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); + return retval; } EXPORT_SYMBOL_GPL(serial8250_do_startup); @@ -2207,6 +2275,7 @@ void serial8250_do_shutdown(struct uart_port *port) container_of(port, struct uart_8250_port, port); unsigned long flags; + pm_runtime_get_sync(port->dev); /* * Disable interrupts from this port */ @@ -2246,6 +2315,8 @@ void serial8250_do_shutdown(struct uart_port *port) * the IRQ chain. */ serial_port_in(port, UART_RX); + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); del_timer_sync(&up->timer); up->timer.function = serial8250_timeout; @@ -2365,6 +2436,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, * Ok, we're now changing the port state. Do it with * interrupts disabled. */ + pm_runtime_get_sync(port->dev); spin_lock_irqsave(&port->lock, flags); /* @@ -2486,6 +2558,9 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, } serial8250_set_mctrl(port, port->mctrl); spin_unlock_irqrestore(&port->lock, flags); + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); + /* Don't rewrite B0 */ if (tty_termios_baud_rate(termios)) tty_termios_encode_baud_rate(termios, baud, baud);
While comparing the OMAP-serial and the 8250 part of this I noticed that the the latter does not use runtime-pm. Here are the pieces. It is basically a get before first register access and a last_busy + put after last access. If I understand this correct, it should do nothing as long as pm_runtime_use_autosuspend() + pm_runtime_enable() isn't invoked on the device. Cc: mika.westerberg@linux.intel.com Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/tty/serial/8250/8250_core.c | 101 +++++++++++++++++++++++++++++++----- 1 file changed, 88 insertions(+), 13 deletions(-)