diff options
| author | Tony Lindgren <tony@atomide.com> | 2021-07-27 13:35:33 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-08-05 14:01:25 +0200 |
| commit | 1fe0e1fa3209ad8e9124147775bd27b1d9f04bd4 (patch) | |
| tree | aa1f84c9938becb5fe997542424fc6ece35e9522 /drivers/tty | |
| parent | 1a191ddcc76f810654e52aab5a36c399d82e26a0 (diff) | |
serial: 8250_omap: Handle optional overrun-throttle-ms property
Handle optional overrun-throttle-ms property as done for 8250_fsl in commit
6d7f677a2afa ("serial: 8250: Rate limit serial port rx interrupts during
input overruns"). This can be used to rate limit the UART interrupts on
noisy lines that end up producing messages like the following:
ttyS ttyS2: 4 input overrun(s)
At least on droid4, the multiplexed USB and UART port is left to UART mode
by the bootloader for a debug console, and if a USB charger is connected
on boot, we get noise on the UART until the PMIC related drivers for PHY
and charger are loaded.
With this patch and overrun-throttle-ms = <500> we avoid the extra rx
interrupts.
Cc: Carl Philipp Klemm <philipp@uvos.xyz>
Cc: Merlijn Wajer <merlijn@wizzup.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20210727103533.51547-2-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/8250/8250_omap.c | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index b81d1bdc7b88..891fd8345e25 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -617,7 +617,7 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id) struct uart_port *port = dev_id; struct omap8250_priv *priv = port->private_data; struct uart_8250_port *up = up_to_u8250p(port); - unsigned int iir; + unsigned int iir, lsr; int ret; #ifdef CONFIG_SERIAL_8250_DMA @@ -628,6 +628,7 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id) #endif serial8250_rpm_get(up); + lsr = serial_port_in(port, UART_LSR); iir = serial_port_in(port, UART_IIR); ret = serial8250_handle_irq(port, iir); @@ -642,6 +643,24 @@ static irqreturn_t omap8250_irq(int irq, void *dev_id) serial_port_in(port, UART_RX); } + /* Stop processing interrupts on input overrun */ + if ((lsr & UART_LSR_OE) && up->overrun_backoff_time_ms > 0) { + unsigned long delay; + + up->ier = port->serial_in(port, UART_IER); + if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) { + port->ops->stop_rx(port); + } else { + /* Keep restarting the timer until + * the input overrun subsides. + */ + cancel_delayed_work(&up->overrun_backoff); + } + + delay = msecs_to_jiffies(up->overrun_backoff_time_ms); + schedule_delayed_work(&up->overrun_backoff, delay); + } + serial8250_rpm_put(up); return IRQ_RETVAL(ret); @@ -1353,6 +1372,10 @@ static int omap8250_probe(struct platform_device *pdev) } } + if (of_property_read_u32(np, "overrun-throttle-ms", + &up.overrun_backoff_time_ms) != 0) + up.overrun_backoff_time_ms = 0; + priv->wakeirq = irq_of_parse_and_map(np, 1); pdata = of_device_get_match_data(&pdev->dev); |