diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.14/950-0311-sc16is7xx-Fix-for-Unexpected-interrupt-8.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.14/950-0311-sc16is7xx-Fix-for-Unexpected-interrupt-8.patch | 110 |
1 files changed, 0 insertions, 110 deletions
diff --git a/target/linux/brcm2708/patches-4.14/950-0311-sc16is7xx-Fix-for-Unexpected-interrupt-8.patch b/target/linux/brcm2708/patches-4.14/950-0311-sc16is7xx-Fix-for-Unexpected-interrupt-8.patch deleted file mode 100644 index b01e523a1e..0000000000 --- a/target/linux/brcm2708/patches-4.14/950-0311-sc16is7xx-Fix-for-Unexpected-interrupt-8.patch +++ /dev/null @@ -1,110 +0,0 @@ -From d4601b298709e44a998df772ac1c85707603fde4 Mon Sep 17 00:00:00 2001 -From: Phil Elwell <phil@raspberrypi.org> -Date: Fri, 18 May 2018 10:26:59 +0100 -Subject: [PATCH 311/454] sc16is7xx: Fix for "Unexpected interrupt: 8" - -The SC16IS752 has an Enhanced Feature Register which is aliased at the -same address as the Interrupt Identification Register; accessing it -requires that a magic value is written to the Line Configuration -Register. If an interrupt is raised while the EFR is mapped in then -the ISR won't be able to access the IIR, leading to the "Unexpected -interrupt" error messages. - -Avoid the problem by claiming a mutex around accesses to the EFR -register, also claiming the mutex in the interrupt handler work -item (this is equivalent to disabling interrupts to interlock against -a non-threaded interrupt handler). - -See: https://github.com/raspberrypi/linux/issues/2529 - -Signed-off-by: Phil Elwell <phil@raspberrypi.org> ---- - drivers/tty/serial/sc16is7xx.c | 28 ++++++++++++++++++++++++++++ - 1 file changed, 28 insertions(+) - ---- a/drivers/tty/serial/sc16is7xx.c -+++ b/drivers/tty/serial/sc16is7xx.c -@@ -333,6 +333,7 @@ struct sc16is7xx_port { - struct kthread_worker kworker; - struct task_struct *kworker_task; - struct kthread_work irq_work; -+ struct mutex efr_lock; - struct sc16is7xx_one p[0]; - }; - -@@ -504,6 +505,21 @@ static int sc16is7xx_set_baud(struct uar - div /= 4; - } - -+ /* In an amazing feat of design, the Enhanced Features Register shares -+ * the address of the Interrupt Identification Register, and is -+ * switched in by writing a magic value (0xbf) to the Line Control -+ * Register. Any interrupt firing during this time will see the EFR -+ * where it expects the IIR to be, leading to "Unexpected interrupt" -+ * messages. -+ * -+ * Prevent this possibility by claiming a mutex while accessing the -+ * EFR, and claiming the same mutex from within the interrupt handler. -+ * This is similar to disabling the interrupt, but that doesn't work -+ * because the bulk of the interrupt processing is run as a workqueue -+ * job in thread context. -+ */ -+ mutex_lock(&s->efr_lock); -+ - lcr = sc16is7xx_port_read(port, SC16IS7XX_LCR_REG); - - /* Open the LCR divisors for configuration */ -@@ -519,6 +535,8 @@ static int sc16is7xx_set_baud(struct uar - /* Put LCR back to the normal mode */ - sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr); - -+ mutex_unlock(&s->efr_lock); -+ - sc16is7xx_port_update(port, SC16IS7XX_MCR_REG, - SC16IS7XX_MCR_CLKSEL_BIT, - prescaler); -@@ -701,6 +719,8 @@ static void sc16is7xx_ist(struct kthread - { - struct sc16is7xx_port *s = to_sc16is7xx_port(ws, irq_work); - -+ mutex_lock(&s->efr_lock); -+ - while (1) { - bool keep_polling = false; - int i; -@@ -710,6 +730,8 @@ static void sc16is7xx_ist(struct kthread - if (!keep_polling) - break; - } -+ -+ mutex_unlock(&s->efr_lock); - } - - static irqreturn_t sc16is7xx_irq(int irq, void *dev_id) -@@ -904,6 +926,9 @@ static void sc16is7xx_set_termios(struct - if (!(termios->c_cflag & CREAD)) - port->ignore_status_mask |= SC16IS7XX_LSR_BRK_ERROR_MASK; - -+ /* As above, claim the mutex while accessing the EFR. */ -+ mutex_lock(&s->efr_lock); -+ - sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, - SC16IS7XX_LCR_CONF_MODE_B); - -@@ -925,6 +950,8 @@ static void sc16is7xx_set_termios(struct - /* Update LCR register */ - sc16is7xx_port_write(port, SC16IS7XX_LCR_REG, lcr); - -+ mutex_unlock(&s->efr_lock); -+ - /* Get baud rate generator configuration */ - baud = uart_get_baud_rate(port, termios, old, - port->uartclk / 16 / 4 / 0xffff, -@@ -1187,6 +1214,7 @@ static int sc16is7xx_probe(struct device - s->regmap = regmap; - s->devtype = devtype; - dev_set_drvdata(dev, s); -+ mutex_init(&s->efr_lock); - - kthread_init_worker(&s->kworker); - kthread_init_work(&s->irq_work, sc16is7xx_ist); |