| Message ID | OF28B2B8C9.5BC0CD28-ON00258A46.0037688F-00258A46.0039155B@gdc.ru (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | tty: serial: meson: hard LOCKUP on crtscts mode | expand |
Hello Pavel, On Thu, Oct 12, 2023 at 10:23:30AM +0000, pkrasavin@imaqliq.ru wrote: > There might be hard lockup if we set crtscts mode on port without RTS/CTS configured: > > # stty -F /dev/ttyAML6 crtscts; echo 1 > /dev/ttyAML6; echo 2 > /dev/ttyAML6 > [ 95.890386] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: > [ 95.890857] rcu: 3-...0: (201 ticks this GP) idle=e33c/1/0x4000000000000000 softirq=5844/5846 fqs=4984 > [ 95.900212] rcu: (detected by 2, t=21016 jiffies, g=7753, q=296 ncpus=4) > [ 95.906972] Task dump for CPU 3: > [ 95.910178] task:bash state:R running task stack:0 pid:205 ppid:1 flags:0x00000202 > [ 95.920059] Call trace: > [ 95.922485] __switch_to+0xe4/0x168 > [ 95.925951] 0xffffff8003477508 > [ 95.974379] watchdog: Watchdog detected hard LOCKUP on cpu 3 > [ 95.974424] Modules linked in: 88x2cs(O) rtc_meson_vrtc > > Possible solution would be to not allow to setup crtscts on such port. > > Tested on S905X3 based board. > > Signed-off-by: Pavel Krasavin <pkrasavin@imaqliq.com> > > --- a/drivers/tty/serial/meson_uart.c 2023-08-22 12:46:50.933814528 +0300 > +++ b/drivers/tty/serial/meson_uart.c 2023-08-22 14:48:15.593169948 +0300 > @@ -380,10 +380,15 @@ static void meson_uart_set_termios(struc > else > val |= AML_UART_STOP_BIT_1SB; > > - if (cflags & CRTSCTS) > - val &= ~AML_UART_TWO_WIRE_EN; > - else > + if (cflags & CRTSCTS) { > + if (port->flags & UPF_HARD_FLOW) { > + val &= ~AML_UART_TWO_WIRE_EN; > + } else { > + termios->c_cflag &= ~CRTSCTS; > + } Please do not use braces where is single statement. In other words: if (cflags & CRTSCTS) { if (port->flags & UPF_HARD_FLOW) val &= ~AML_UART_TWO_WIRE_EN; else termios->c_cflag &= ~CRTSCTS; } else { val |= AML_UART_TWO_WIRE_EN; } > + } else { > val |= AML_UART_TWO_WIRE_EN; > + } > > writel(val, port->membase + AML_UART_CONTROL); > > @@ -705,6 +710,7 @@ static int meson_uart_probe(struct platf > u32 fifosize = 64; /* Default is 64, 128 for EE UART_0 */ > int ret = 0; > int irq; > + bool has_rtscts; > > if (pdev->dev.of_node) > pdev->id = of_alias_get_id(pdev->dev.of_node, "serial"); > @@ -732,6 +738,7 @@ static int meson_uart_probe(struct platf > return irq; > > of_property_read_u32(pdev->dev.of_node, "fifo-size", &fifosize); > + has_rtscts = of_property_read_bool(pdev->dev.of_node, "uart-has-rtscts"); > > if (meson_ports[pdev->id]) { > return dev_err_probe(&pdev->dev, -EBUSY, > @@ -762,6 +769,8 @@ static int meson_uart_probe(struct platf > port->mapsize = resource_size(res_mem); > port->irq = irq; > port->flags = UPF_BOOT_AUTOCONF | UPF_LOW_LATENCY; > + if (has_rtscts) > + port->flags |= UPF_HARD_FLOW; > port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_MESON_CONSOLE); > port->dev = &pdev->dev; > port->line = pdev->id; > > _______________________________________________ > linux-amlogic mailing list > linux-amlogic@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-amlogic
Hello Dmitry, ----- "Dmitry Rokosov" <ddrokosov@salutedevices.com> писал(а): ----- > Please do not use braces where is single statement. In other words: > > if (cflags & CRTSCTS) { > if (port->flags & UPF_HARD_FLOW) > val &= ~AML_UART_TWO_WIRE_EN; > else > termios->c_cflag &= ~CRTSCTS; > } else { > val |= AML_UART_TWO_WIRE_EN; > } thank you for your note, I will provide v2 without braces. -- Regards, Pavel.
--- a/drivers/tty/serial/meson_uart.c 2023-08-22 12:46:50.933814528 +0300 +++ b/drivers/tty/serial/meson_uart.c 2023-08-22 14:48:15.593169948 +0300 @@ -380,10 +380,15 @@ static void meson_uart_set_termios(struc else val |= AML_UART_STOP_BIT_1SB; - if (cflags & CRTSCTS) - val &= ~AML_UART_TWO_WIRE_EN; - else + if (cflags & CRTSCTS) { + if (port->flags & UPF_HARD_FLOW) { + val &= ~AML_UART_TWO_WIRE_EN; + } else { + termios->c_cflag &= ~CRTSCTS; + } + } else { val |= AML_UART_TWO_WIRE_EN; + } writel(val, port->membase + AML_UART_CONTROL); @@ -705,6 +710,7 @@ static int meson_uart_probe(struct platf u32 fifosize = 64; /* Default is 64, 128 for EE UART_0 */ int ret = 0; int irq; + bool has_rtscts; if (pdev->dev.of_node) pdev->id = of_alias_get_id(pdev->dev.of_node, "serial"); @@ -732,6 +738,7 @@ static int meson_uart_probe(struct platf return irq; of_property_read_u32(pdev->dev.of_node, "fifo-size", &fifosize); + has_rtscts = of_property_read_bool(pdev->dev.of_node, "uart-has-rtscts"); if (meson_ports[pdev->id]) { return dev_err_probe(&pdev->dev, -EBUSY, @@ -762,6 +769,8 @@ static int meson_uart_probe(struct platf port->mapsize = resource_size(res_mem); port->irq = irq; port->flags = UPF_BOOT_AUTOCONF | UPF_LOW_LATENCY; + if (has_rtscts) + port->flags |= UPF_HARD_FLOW; port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_MESON_CONSOLE); port->dev = &pdev->dev; port->line = pdev->id;
There might be hard lockup if we set crtscts mode on port without RTS/CTS configured: # stty -F /dev/ttyAML6 crtscts; echo 1 > /dev/ttyAML6; echo 2 > /dev/ttyAML6 [ 95.890386] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [ 95.890857] rcu: 3-...0: (201 ticks this GP) idle=e33c/1/0x4000000000000000 softirq=5844/5846 fqs=4984 [ 95.900212] rcu: (detected by 2, t=21016 jiffies, g=7753, q=296 ncpus=4) [ 95.906972] Task dump for CPU 3: [ 95.910178] task:bash state:R running task stack:0 pid:205 ppid:1 flags:0x00000202 [ 95.920059] Call trace: [ 95.922485] __switch_to+0xe4/0x168 [ 95.925951] 0xffffff8003477508 [ 95.974379] watchdog: Watchdog detected hard LOCKUP on cpu 3 [ 95.974424] Modules linked in: 88x2cs(O) rtc_meson_vrtc Possible solution would be to not allow to setup crtscts on such port. Tested on S905X3 based board. Signed-off-by: Pavel Krasavin <pkrasavin@imaqliq.com>