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From: Zhang Zhen <zhenzhang.zhang@huawei.com>
To: <linux-serial@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Cc: <tim.kryger@linaro.org>, <gregkh@linuxfoundation.org>,
	<jamie@jamieiles.com>, <alan@linux.intel.com>, <arnd@arndb.de>,
	<shenjiangjiang@huawei.com>, <long.wanglong@huawei.com>
Subject: [RFC] With 8250 Designware UART, if writes to the LCR failed the kernel will hung up
Date: Fri, 6 Mar 2015 17:11:55 +0800	[thread overview]
Message-ID: <54F96F5B.2090601@huawei.com> (raw)

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!

	

	


             reply	other threads:[~2015-03-06  9:25 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-06  9:11 Zhang Zhen [this message]
2015-03-06 16:50 ` Peter Hurley
2015-03-07  3:01   ` Tim Kryger
2015-03-09  7:10     ` long.wanglong
2015-03-09 13:32       ` Alan Cox
2015-03-09 14:36         ` Tim Kryger
2015-03-09 15:05           ` Alan Cox
2015-03-10  2:47             ` Tim Kryger
2015-03-10  3:15               ` Zhang Zhen
2015-03-10 13:25               ` Peter Hurley
2015-03-11  1:20                 ` Zhang Zhen
2015-03-13 15:36               ` Andy Shevchenko
2015-03-15 14:50                 ` Peter Hurley

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