? 2013?06?27? 22:15, Shawn Guo ??:

quoted

  	* Check whether an invalid uart number has been specified, and

quoted

 @@ -1371,6 +1381,15 @@ imx_console_setup(struct console *co, char *options)
   	if (sport == NULL)
   		return -ENODEV;
 
 +	retval = clk_prepare_enable(sport->clk_per);
 +	if (retval)
 +		goto error_console;
 +	retval = clk_prepare_enable(sport->clk_ipg);
 +	if (retval) {
 +		clk_disable_unprepare(sport->clk_per);
 +		goto error_console;
 +	}
 +

Why do we need clk_enable() here at all?  The amba-pl011 driver only
calls clk_prepare() in console .setup().

We need to set the imx_setUp_ufcr() in our imx_console_setup(),
so we need to enable the clocks, aren't we?

quoted

quoted

   	if (options)
   		uart_parse_options(options,&baud,&parity,&bits,&flow);
   	else
 @@ -1378,7 +1397,17 @@ imx_console_setup(struct console *co, char *options)
 
   	imx_setup_ufcr(sport, 0);
 
 -	return uart_set_options(&sport->port, co, baud, parity, bits, flow);
 +	retval = uart_set_options(&sport->port, co, baud, parity, bits, flow);
 +
 +	clk_disable(sport->clk_per);
 +	clk_disable(sport->clk_ipg);
 +	if (retval) {
 +		clk_unprepare(sport->clk_per);
 +		clk_unprepare(sport->clk_ipg);
 +	}
 +
 +error_console:
 +	return retval;
   }
 
   static struct uart_driver imx_reg;
 @@ -1583,10 +1612,8 @@ static int serial_imx_probe(struct platform_device *pdev)
   		goto deinit;
   	platform_set_drvdata(pdev, sport);
 
 -	if (!uart_console(&sport->port)) {
 -		clk_disable_unprepare(sport->clk_per);
 -		clk_disable_unprepare(sport->clk_ipg);
 -	}
 +	clk_disable_unprepare(sport->clk_per);
 +	clk_disable_unprepare(sport->clk_ipg);

I also had a hard time to understand why we need to turn on the clocks
in .probe() for a while and then turn them off.

In the probe's uart_add_one_port(), we will register the console and 
call the setup() hook,
so it's ok to disable the clocks in the end of the probe.

It just reminds me a thing.  Did you test CONFIG_CONSOLE_POLL support
when your commit 28eb427 (serial: imx: enable the clocks only when the
uart is used) went in?  The commit turns off the clocks at the

sorry, i did not do this.

end of .probe(), but who will enable the clocks for .poll_get_char()
and .poll_put_char()?  The amba-pl011 driver does that in .poll_init().

dido. in the uart_add_one_port().

thanks
Huang Shijie