From: Huang Shijie <b32955@freescale.com>
To: Shawn Guo <shawn.guo@linaro.org>
Cc: gregkh@linuxfoundation.org, linux-serial@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
fabio.estevam@freescale.com
Subject: Re: [PATCH 1/2] serial: imx: remove the uart_console() check
Date: Fri, 28 Jun 2013 10:17:49 +0800 [thread overview]
Message-ID: <51CCF24D.1060007@freescale.com> (raw)
In-Reply-To: <20130627141535.GD2695@S2101-09.ap.freescale.net>
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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next prev parent reply other threads:[~2013-06-28 2:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-26 9:35 [PATCH 1/2] serial: imx: remove the uart_console() check Huang Shijie
2013-06-26 9:35 ` [PATCH 2/2] serial: imx: check the return value when enabling the clocks Huang Shijie
2013-06-27 14:15 ` [PATCH 1/2] serial: imx: remove the uart_console() check Shawn Guo
2013-06-28 2:17 ` Huang Shijie [this message]
2013-06-28 2:55 ` Shawn Guo
2013-06-28 5:53 ` Huang Shijie
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