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tty: serial: meson: fix hard LOCKUP on crtscts mode

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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.

Fixes: ff7693d079 ("ARM: meson: serial: add MesonX SoC on-chip uart driver")
Cc: stable@vger.kernel.org
Signed-off-by: Pavel Krasavin <pkrasavin@imaqliq.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Dmitry Rokosov <ddrokosov@salutedevices.com>

v6: stable tag added
v5: https://lore.kernel.org/lkml/OF43DA36FF.2BD3BB21-ON00258A47.005A8125-00258A47.005A9513@gdc.ru/
added missed Reviewed-by tags, Fixes tag added according to Dmitry and Neil notes
v4: https://lore.kernel.org/lkml/OF55521400.7512350F-ON00258A47.003F7254-00258A47.0040E15C@gdc.ru/
More correct patch subject according to Jiri's note
v3: https://lore.kernel.org/lkml/OF6CF5FFA0.CCFD0E8E-ON00258A46.00549EDF-00258A46.0054BB62@gdc.ru/
"From:" line added to the mail
v2: https://lore.kernel.org/lkml/OF950BEF72.7F425944-ON00258A46.00488A76-00258A46.00497D44@gdc.ru/
braces for single statement removed according to Dmitry's note
v1: https://lore.kernel.org/lkml/OF28B2B8C9.5BC0CD28-ON00258A46.0037688F-00258A46.0039155B@gdc.ru/
Link: https://lore.kernel.org/r/OF66360032.51C36182-ON00258A48.003F656B-00258A48.0040092C@gdc.ru

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pavel Krasavin 2023-10-14 11:39:26 +00:00 committed by Greg Kroah-Hartman
parent b0c9a045e8
commit 2a1d728f20
1 changed files with 11 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/tty/serial/meson_uart.c
View File

@ -380,10 +380,14 @@ static void meson_uart_set_termios(struct uart_port *port,
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 +709,7 @@ static int meson_uart_probe(struct platform_device *pdev)
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 +737,7 @@ static int meson_uart_probe(struct platform_device *pdev)
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 +768,8 @@ static int meson_uart_probe(struct platform_device *pdev)
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;