From 8679328eb859d06a1984ab48d90ac35d11bbcaf1 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Thu, 21 Sep 2023 16:52:33 +0200 Subject: serial: Reduce spinlocked portion of uart_rs485_config() Commit 44b27aec9d96 ("serial: core, 8250: set RS485 termination GPIO in serial core") enabled support for RS485 termination GPIOs behind i2c expanders by setting the GPIO outside of the critical section protected by the port spinlock. Access to the i2c expander may sleep, which caused a splat with the port spinlock held. Commit 7c7f9bc986e6 ("serial: Deassert Transmit Enable on probe in driver-specific way") erroneously regressed that by spinlocking the GPIO manipulation again. Fix by moving uart_rs485_config() (the function manipulating the GPIO) outside of the spinlocked section and acquiring the spinlock inside of uart_rs485_config() for the invocation of ->rs485_config() only. This gets us one step closer to pushing the spinlock down into the ->rs485_config() callbacks which actually need it. (Some callbacks do not want to be spinlocked because they perform sleepable register accesses, see e.g. sc16is7xx_config_rs485().) Stack trace for posterity: Voluntary context switch within RCU read-side critical section! WARNING: CPU: 0 PID: 56 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch Call trace: rcu_note_context_switch __schedule schedule schedule_timeout wait_for_completion_timeout bcm2835_i2c_xfer __i2c_transfer i2c_transfer i2c_transfer_buffer_flags regmap_i2c_write _regmap_raw_write_impl _regmap_bus_raw_write _regmap_write _regmap_update_bits regmap_update_bits_base pca953x_gpio_set_value gpiod_set_raw_value_commit gpiod_set_value_nocheck gpiod_set_value_cansleep uart_rs485_config uart_add_one_port pl011_register_port pl011_probe Fixes: 7c7f9bc986e6 ("serial: Deassert Transmit Enable on probe in driver-specific way") Suggested-by: Lino Sanfilippo Signed-off-by: Lukas Wunner Cc: stable@vger.kernel.org # v6.1+ Link: https://lore.kernel.org/r/f3a35967c28b32f3c6432d0aa5936e6a9908282d.1695307688.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 7bdc21d5e13b..ca26a8aef2cb 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1404,12 +1404,18 @@ static void uart_set_rs485_termination(struct uart_port *port, static int uart_rs485_config(struct uart_port *port) { struct serial_rs485 *rs485 = &port->rs485; + unsigned long flags; int ret; + if (!(rs485->flags & SER_RS485_ENABLED)) + return 0; + uart_sanitize_serial_rs485(port, rs485); uart_set_rs485_termination(port, rs485); + spin_lock_irqsave(&port->lock, flags); ret = port->rs485_config(port, NULL, rs485); + spin_unlock_irqrestore(&port->lock, flags); if (ret) memset(rs485, 0, sizeof(*rs485)); @@ -2474,11 +2480,10 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport) if (ret == 0) { if (tty) uart_change_line_settings(tty, state, NULL); + uart_rs485_config(uport); spin_lock_irq(&uport->lock); if (!(uport->rs485.flags & SER_RS485_ENABLED)) ops->set_mctrl(uport, uport->mctrl); - else - uart_rs485_config(uport); ops->start_tx(uport); spin_unlock_irq(&uport->lock); tty_port_set_initialized(port, true); @@ -2587,10 +2592,10 @@ uart_configure_port(struct uart_driver *drv, struct uart_state *state, port->mctrl &= TIOCM_DTR; if (!(port->rs485.flags & SER_RS485_ENABLED)) port->ops->set_mctrl(port, port->mctrl); - else - uart_rs485_config(port); spin_unlock_irqrestore(&port->lock, flags); + uart_rs485_config(port); + /* * If this driver supports console, and it hasn't been * successfully registered yet, try to re-register it. -- cgit v1.2.3-70-g09d2 From 560706eff7c8e5621b0d63afe0866e0e1906e87e Mon Sep 17 00:00:00 2001 From: Tony Lindgren Date: Tue, 26 Sep 2023 09:13:17 +0300 Subject: serial: 8250_omap: Fix errors with no_console_suspend We now get errors on system suspend if no_console_suspend is set as reported by Thomas. The errors started with commit 20a41a62618d ("serial: 8250_omap: Use force_suspend and resume for system suspend"). Let's fix the issue by checking for console_suspend_enabled in the system suspend and resume path. Note that with this fix the checks for console_suspend_enabled in omap8250_runtime_suspend() become useless. We now keep runtime PM usage count for an attached kernel console starting with commit bedb404e91bb ("serial: 8250_port: Don't use power management for kernel console"). Fixes: 20a41a62618d ("serial: 8250_omap: Use force_suspend and resume for system suspend") Cc: stable Cc: Udit Kumar Reported-by: Thomas Richard Signed-off-by: Tony Lindgren Tested-by: Thomas Richard Reviewed-by: Dhruva Gole Link: https://lore.kernel.org/r/20230926061319.15140-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_omap.c | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index 26dd089d8e82..ca972fd37725 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -1617,7 +1617,7 @@ static int omap8250_suspend(struct device *dev) { struct omap8250_priv *priv = dev_get_drvdata(dev); struct uart_8250_port *up = serial8250_get_port(priv->line); - int err; + int err = 0; serial8250_suspend_port(priv->line); @@ -1627,7 +1627,8 @@ static int omap8250_suspend(struct device *dev) if (!device_may_wakeup(dev)) priv->wer = 0; serial_out(up, UART_OMAP_WER, priv->wer); - err = pm_runtime_force_suspend(dev); + if (uart_console(&up->port) && console_suspend_enabled) + err = pm_runtime_force_suspend(dev); flush_work(&priv->qos_work); return err; @@ -1636,11 +1637,15 @@ static int omap8250_suspend(struct device *dev) static int omap8250_resume(struct device *dev) { struct omap8250_priv *priv = dev_get_drvdata(dev); + struct uart_8250_port *up = serial8250_get_port(priv->line); int err; - err = pm_runtime_force_resume(dev); - if (err) - return err; + if (uart_console(&up->port) && console_suspend_enabled) { + err = pm_runtime_force_resume(dev); + if (err) + return err; + } + serial8250_resume_port(priv->line); /* Paired with pm_runtime_resume_and_get() in omap8250_suspend() */ pm_runtime_mark_last_busy(dev); @@ -1717,16 +1722,6 @@ static int omap8250_runtime_suspend(struct device *dev) if (priv->line >= 0) up = serial8250_get_port(priv->line); - /* - * When using 'no_console_suspend', the console UART must not be - * suspended. Since driver suspend is managed by runtime suspend, - * preventing runtime suspend (by returning error) will keep device - * active during suspend. - */ - if (priv->is_suspending && !console_suspend_enabled) { - if (up && uart_console(&up->port)) - return -EBUSY; - } if (priv->habit & UART_ERRATA_CLOCK_DISABLE) { int ret; -- cgit v1.2.3-70-g09d2 From 81a61051e0ce5fd7e09225c0d5985da08c7954a7 Mon Sep 17 00:00:00 2001 From: Tony Lindgren Date: Thu, 5 Oct 2023 10:56:42 +0300 Subject: serial: core: Fix checks for tx runtime PM state Maximilian reported that surface_serial_hub serdev tx does not work during system suspend. During system suspend, runtime PM gets disabled in __device_suspend_late(), and tx is unable to wake-up the serial core port device that we use to check if tx is safe to start. Johan summarized the regression noting that serdev tx no longer always works as earlier when the serdev device is runtime PM active. The serdev device and the serial core controller devices are siblings of the serial port hardware device. The runtime PM usage count from serdev device does not propagate to the serial core device siblings, it only propagates to the parent. In addition to the tx issue for suspend, testing for the serial core port device can cause an unnecessary delay in enabling tx while waiting for the serial core port device to wake-up. The serial core port device wake-up is only needed to flush pending tx when the serial port hardware device was in runtime PM suspended state. To fix the regression, we need to check the runtime PM state of the parent serial port hardware device for tx instead of the serial core port device. As the serial port device drivers may or may not implement runtime PM, we need to also add a check for pm_runtime_enabled(). Reported-by: Maximilian Luz Cc: stable Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM") Signed-off-by: Tony Lindgren Tested-by: Maximilian Luz Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20231005075644.25936-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index ca26a8aef2cb..d5ba6e90bd95 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -156,7 +156,7 @@ static void __uart_start(struct uart_state *state) * enabled, serial_port_runtime_resume() calls start_tx() again * after enabling the device. */ - if (pm_runtime_active(&port_dev->dev)) + if (!pm_runtime_enabled(port->dev) || pm_runtime_active(port->dev)) port->ops->start_tx(port); pm_runtime_mark_last_busy(&port_dev->dev); pm_runtime_put_autosuspend(&port_dev->dev); -- cgit v1.2.3-70-g09d2 From b3fa3cf02e3ce92d32bfdeedd5a6bd0825f55a14 Mon Sep 17 00:00:00 2001 From: Janusz Krzysztofik Date: Sat, 7 Oct 2023 23:38:18 +0200 Subject: ASoC: ti: ams-delta: Fix cx81801_receive() argument types Since types of arguments accepted by tty_ldis_ops::receive_buf() have changed, the driver no longer builds. .../linux/sound/soc/ti/ams-delta.c:403:24: error: initialization of 'void (*)(struct tty_struct *, const u8 *, const u8 *, size_t)' {aka 'void (*)(struct tty_struct *, const unsigned char *, const unsigned char *, unsigned int)'} from incompatible pointer type 'void (*)(struct tty_struct *, const u8 *, const char *, int)' {aka 'void (*)(struct tty_struct *, const unsigned char *, const char *, int)'} [-Werror=incompatible-pointer-types] 403 | .receive_buf = cx81801_receive, Fix it. Fixes: e8161447bb0c ("tty: make tty_ldisc_ops::*buf*() hooks operate on size_t") Fixes: 892bc209f250 ("tty: use u8 for flags") Signed-off-by: Janusz Krzysztofik Link: https://lore.kernel.org/r/20231007213820.376360-1-jmkrzyszt@gmail.com Signed-off-by: Greg Kroah-Hartman --- sound/soc/ti/ams-delta.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/sound/soc/ti/ams-delta.c b/sound/soc/ti/ams-delta.c index 371943350fdf..666057d50ea0 100644 --- a/sound/soc/ti/ams-delta.c +++ b/sound/soc/ti/ams-delta.c @@ -336,8 +336,8 @@ static void cx81801_hangup(struct tty_struct *tty) } /* Line discipline .receive_buf() */ -static void cx81801_receive(struct tty_struct *tty, const u8 *cp, - const char *fp, int count) +static void cx81801_receive(struct tty_struct *tty, const u8 *cp, const u8 *fp, + size_t count) { struct snd_soc_component *component = tty->disc_data; const unsigned char *c; -- cgit v1.2.3-70-g09d2