Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Fri, 2 Jun 2023 12:27:01 +0300 | From | Tony Lindgren <> | Subject | Re: [PATCH v12 1/1] serial: core: Start managing serial controllers to enable runtime PM |
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Hi,
* Chen-Yu Tsai <wenst@chromium.org> [230602 08:33]: > This patch, in linux-next since 20230601, unfortunately breaks MediaTek > based Chromebooks. The kernel hangs during the probe of the serial ports, > which use the 8250_mtk driver. This happens even with the subsequent > fixes in next-20230602 and on the mailing list: > > serial: core: Fix probing serial_base_bus devices > serial: core: Don't drop port_mutex in serial_core_remove_one_port > serial: core: Fix error handling for serial_core_ctrl_device_add()
OK thanks for reporting it.
> Without the fixes, the kernel gives "WARNING: bad unlock balance detected!" > With the fixes, it just silently hangs. The last messages seen on the > (serial) console are: > > Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled > printk: console [ttyS0] disabled > mt6577-uart 11002000.serial: using DT '/soc/serial@11002000' for 'rs485-term' GPIO lookup > of_get_named_gpiod_flags: can't parse 'rs485-term-gpios' property of node '/soc/serial@11002000[0]' > of_get_named_gpiod_flags: can't parse 'rs485-term-gpio' property of node '/soc/serial@11002000[0]' > mt6577-uart 11002000.serial: using lookup tables for GPIO lookup > mt6577-uart 11002000.serial: No GPIO consumer rs485-term found > mt6577-uart 11002000.serial: using DT '/soc/serial@11002000' for 'rs485-rx-during-tx' GPIO lookup > of_get_named_gpiod_flags: can't parse 'rs485-rx-during-tx-gpios' property of node '/soc/serial@11002000[0]' > of_get_named_gpiod_flags: can't parse 'rs485-rx-during-tx-gpio' property of node '/soc/serial@11002000[0]' > mt6577-uart 11002000.serial: using lookup tables for GPIO lookup > mt6577-uart 11002000.serial: No GPIO consumer rs485-rx-during-tx found > > What can we do to help resolve this?
There may be something blocking serial_ctrl and serial_port from probing. That was the issue with the arch_initcall() using drivers.
Not sure yet what the issue here might be, but the 8250_mtk should be fairly similar use case to the 8250_omap driver that I've tested with. But unfortunately I don't think I have any 8250_mtk using devices to test with.
The following hack should allow you to maybe see more info on what goes wrong and allows adding some debug printk to serial_base_match() for example to see if that gets called for mt6577-uart.
Hmm maybe early_mtk8250_setup() somehow triggers the issue? Not sure why early_serial8250_setup() would cause issues here though.
Regards,
Tony
8< ----------------- diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -144,7 +144,7 @@ static void __uart_start(struct tty_struct *tty) return; port_dev = port->port_dev; - +#if 0 /* Increment the runtime PM usage count for the active check below */ err = pm_runtime_get(&port_dev->dev); if (err < 0) { @@ -161,6 +161,9 @@ static void __uart_start(struct tty_struct *tty) port->ops->start_tx(port); pm_runtime_mark_last_busy(&port_dev->dev); pm_runtime_put_autosuspend(&port_dev->dev); +#else + port->ops->start_tx(port); +#endif } static void uart_start(struct tty_struct *tty) -- 2.41.0
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