linux-kernel - RE: [PATCH] serial: 8250: Add cpufreq support

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Message-ID: <000c01ca9840$a1fb99b0$e5f2cd10$@com>
Date:	Mon, 18 Jan 2010 18:47:49 +0530
From:	"Chaithrika U S" <chaithrika@...com>
To:	"'Alan Cox'" <alan@...rguk.ukuu.org.uk>
Cc:	<linux-serial@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<davinci-linux-open-source@...ux.davincidsp.com>,
	<khilman@...prootsystems.com>, <akpm@...ux-foundation.org>
Subject: RE: [PATCH] serial: 8250: Add cpufreq support

On Wed, Jan 13, 2010 at 19:14:45, Alan Cox wrote:
> > +static int serial8250_cpufreq_transition(struct notifier_block *nb,
> > +					     unsigned long val, void *data)
> > +{
> > +	struct uart_8250_port *p;
> > +	struct uart_port *uport;
> > +
> > +	p = container_of(nb, struct uart_8250_port, freq_transition);
> > +	uport = &p->port;
> > +
> > +	if (IS_ERR(p->clk))
> > +		goto cpu_freq_exit;
> > +
> > +	if (p->port.uartclk == clk_get_rate(p->clk))
> > +		goto cpu_freq_exit;
> > +
> > +	p->port.uartclk = clk_get_rate(p->clk);
> > +	if (val == CPUFREQ_POSTCHANGE) {
> > +		struct ktermios *termios;
> > +		struct tty_struct *tty;
> > +		if (uport->state == NULL)
> > +			goto cpu_freq_exit;
> > +
> > +		tty = uport->state->port.tty;
> 
> Need locking on port->tty.
> 
> > +		if (tty == NULL)
> > +			goto cpu_freq_exit;
> > +
> 
> Need locking on tty->termios
> 
> I'd say this is also probably at the wrong level - why not do it at the
> uart_port level instead (ie move the code you have into serial_core using
> uart_port) - you've made it all nicely generic already.
> 
> Alan
> 	
	
Thank you for the review comments.
I will submit an updated version of patch soon.

Regards, 
Chaithrika


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