linux-kernel - Re: [PATCH v6 10/10] clocksource: timer-dm: Check prescaler value

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Message-ID: <20180107192633.GA19198@lenoch>
Date:   Sun, 7 Jan 2018 20:26:33 +0100
From:   Ladislav Michl <ladis@...ux-mips.org>
To:     Keerthy <j-keerthy@...com>
Cc:     daniel.lezcano@...aro.org, tony@...mide.com, aaro.koskinen@....fi,
        thierry.reding@...il.com, grygorii.strashko@...com,
        linux-omap@...r.kernel.org, robh+dt@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-pwm@...r.kernel.org,
        sebastian.reichel@...labora.co.uk, linux-kernel@...r.kernel.org,
        t-kristo@...com
Subject: Re: [PATCH v6 10/10] clocksource: timer-dm: Check prescaler value

On Sun, Jan 07, 2018 at 09:26:44PM +0530, Keerthy wrote:
> On 1/5/2018 4:17 AM, Ladislav Michl wrote:
> > On Tue, Jan 02, 2018 at 03:39:59PM +0530, Keerthy wrote:
> > > From: Ladislav Michl <ladis@...ux-mips.org>
> > > 
> > > Invalid prescaler value is silently ignored. Fix that
> > > by returning -EINVAL in such case. As invalid value
> > > disabled use of the prescaler, use -1 explicitely for
> > > that purpose.
> > > 
> > > Signed-off-by: Ladislav Michl <ladis@...ux-mips.org>
> > > ---
> > >   drivers/clocksource/timer-dm.c | 3 +++
> > >   1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/drivers/clocksource/timer-dm.c b/drivers/clocksource/timer-dm.c
> > > index 60db173..01a9cb0 100644
> > > --- a/drivers/clocksource/timer-dm.c
> > > +++ b/drivers/clocksource/timer-dm.c
> > > @@ -672,6 +672,9 @@ int omap_dm_timer_set_prescaler(struct omap_dm_timer *timer, int prescaler)
> > >   	if (prescaler >= 0x00 && prescaler <= 0x07) {
> > >   		l |= OMAP_TIMER_CTRL_PRE;
> > >   		l |= prescaler << 2;
> > > +	} else {
> > > +		if (prescaler != -1)
> > > +			return -EINVAL;
> > 
> > Argh... This is actually wrong, as it leaves timer enabled.
> > I suggest simply dropping this patch and I'll rethink whole
> > approach a bit later (and better).
> 
> Okay. I hope the rest 9 patches work well for you.

Yes. I rebased event capture patches on top of this serie (based on
linux-next) and will post them during next week for review. Fixed
patch will be included (note, it is not really needed for your serie
as noone is calling this function).

> > 
> > >   	}
> > >   	omap_dm_timer_write_reg(timer, OMAP_TIMER_CTRL_REG, l);
> > 
> > Sorry for the noise,
> > 	ladis
> >