From mboxrd@z Thu Jan  1 00:00:00 1970
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
Subject: Re: [PATCH] serial: samsung: Fixed wrong comparison for baudclk_rate
Date: Tue, 15 May 2012 12:57:28 +0100
Message-ID: <20120515115728.GJ10453@n2100.arm.linux.org.uk>
References: <000101cd3283$5f58eba0$1e0ac2e0$%kim@samsung.com> <20120515101541.GH10453@n2100.arm.linux.org.uk> <000301cd3291$3a7a6940$af6f3bc0$%kim@samsung.com>
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To: Kyoungil Kim <ki0351.kim@samsung.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-serial@vger.kernel.org, linux-samsung-soc@vger.kernel.org, 'Kukjin Kim' <kgene.kim@samsung.com>, 'Yoon' <junho78.yoon@samsung.com>, 'Alan Cox' <alan@linux.intel.com>

On Tue, May 15, 2012 at 08:52:39PM +0900, Kyoungil Kim wrote:
> Russell King wrote:
> > On Tue, May 15, 2012 at 07:13:28PM +0900, Kyoungil Kim wrote:
> > > port->baudclk_rate should be compared to the rate of port->baudclk,
> > > because port->baudclk_rate was assigned as the rate of port->baudclk previously.
> > > So to check that the current baudclk rate is same as previous rate,
> > > the target of comparison sholud be the rate of port->baudclk.
> > >
> > > Signed-off-by: Jun-Ho, Yoon <junho78.yoon@samsung.com>
> > > Signed-off-by: Kyoungil Kim <ki0351.kim@samsung.com>
> > > ---
> > >  drivers/tty/serial/samsung.c |    4 ++--
> > >  1 files changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
> > > index d8b0aee..c4867ea 100644
> > > --- a/drivers/tty/serial/samsung.c
> > > +++ b/drivers/tty/serial/samsung.c
> > > @@ -1014,10 +1014,10 @@ static int s3c24xx_serial_cpufreq_transition(struct notifier_block *nb,
> > >  	 * a disturbance in the clock-rate over the change.
> > >  	 */
> > >
> > > -	if (IS_ERR(port->clk))
> > > +	if (IS_ERR_OR_NULL(port->baudclk))
> > 
> > NAK.  See my previous emails on the validity of clk_get() return values.
> 
> I read your previous emails, but I don't understand.
> Could you explain more details, please?

Drivers are only allowed to assume that IS_ERR() values for clocks are
invalid.  Everything else they should not concern themselves with.