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Subject[RFC] With 8250 Designware UART, if writes to the LCR failed the kernel will hung up
Hi,

I'm testing 4.0-rc1 kernel on my board with 8250 Designware UART.(ARM Cortex-a15 single core).

I found if serial is busy and writes to the LCR failed after tried 1000 times.
The kernel will hung up.

The system boot success after changed from:

95 static void dw8250_serial_out(struct uart_port *p, int offset, int value)
96 {
97 struct dw8250_data *d = p->private_data;
98
...
...
112 writeb(value, p->membase + (UART_LCR << p->regshift));
113 }
114 dev_err(p->dev, "Couldn't set LCR to %d\n", value);
115 }
116 }

to:

95 static void dw8250_serial_out(struct uart_port *p, int offset, int value)
96 {
97 struct dw8250_data *d = p->private_data;
98
...
...
112 writeb(value, p->membase + (UART_LCR << p->regshift));
113 }
114 dev_info(p->dev, "Couldn't set LCR to %d\n", value); //changed here
115 }
116 }

The reason is serial8250_console_write can't get port->lock because serial8250_do_set_termios has
got port->lock.
So i think here we should change from dev_err to dev_info ?
Any suggestions are welcome.

Best regards!







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