于 2013年06月27日 22:15, Shawn Guo 写道:
* Check whether an invalid uart number has been specified, and
> @@ -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?
> 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
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