linux-kernel - Re: [PATCH V7 5/6] tty: serial: meson: The system stuck when you run the stty command on the console to change the baud rate

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Date:   Tue, 1 Mar 2022 13:44:28 +0800
From:   Yu Tu <yu.tu@...ogic.com>
To:     Jerome Brunet <jbrunet@...libre.com>,
        <linux-serial@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-amlogic@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: Re: [PATCH V7 5/6] tty: serial: meson: The system stuck when you run
 the stty command on the console to change the baud rate

Hi Jerome,
	Thank you for your reply.

On 2022/2/28 18:58, Jerome Brunet wrote:
> [ EXTERNAL EMAIL ]
> 
> 
> On Fri 25 Feb 2022 at 15:39, Yu Tu <yu.tu@...ogic.com> wrote:
> 
>> Start the console and run the following commands in turn:
>> stty -F /dev/ttyAML0 115200 and stty -F /dev/ttyAML0 921600. The
>> system will stuck.
>>
>> Signed-off-by: Yu Tu <yu.tu@...ogic.com>
>> ---
>>   drivers/tty/serial/meson_uart.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
>> index ba8dc203b9cb..d19349ead738 100644
>> --- a/drivers/tty/serial/meson_uart.c
>> +++ b/drivers/tty/serial/meson_uart.c
>> @@ -365,8 +365,13 @@ static void meson_uart_set_termios(struct uart_port *port,
>>   	writel(val, port->membase + AML_UART_CONTROL);
>>   
>>   	baud = uart_get_baud_rate(port, termios, old, 50, 4000000);
>> +
>> +	spin_unlock_irqrestore(&port->lock, flags);
>> +
>>   	meson_uart_change_speed(port, baud);
>>   
>> +	spin_lock_irqsave(&port->lock, flags);
> 
> Already told you before, you can make meson_change_speed()
> clk_set_rate() uses mutex and may sleep.
Sorry, I may have only paid attention to how you asked me to change to 
using the clock before, instead of paying attention to this suggestion.
> 
>> +
>>   	port->read_status_mask = AML_UART_TX_FIFO_WERR;
>>   	if (iflags & INPCK)
>>   		port->read_status_mask |= AML_UART_PARITY_ERR |
>