linux-kernel - Re: [PATCHv3] x86, mrst: share APB timer code with other platforms

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Date:	Mon, 9 May 2011 21:50:15 +0100
From:	Jamie Iles <jamie@...ieiles.com>
To:	john stultz <johnstul@...ibm.com>
Cc:	Jamie Iles <jamie@...ieiles.com>, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: Re: [PATCHv3] x86, mrst: share APB timer code with other platforms

On Mon, May 09, 2011 at 01:22:22PM -0700, john stultz wrote:
> On Tue, 2011-04-12 at 12:10 +0100, Jamie Iles wrote:
> > The APB timers are an IP block from Synopsys (DesignWare APB timers)
> > and are also found in other systems including ARM SoC's.  This patch
> > adds functions for creating clock_event_devices and clocksources from
> > APB timers but does not do the resource allocation.  This is handled
> > in a higher layer to allow the timers to be created from multiple
> > methods such as platform_devices.
> > 
> > Changes since v2:
> > 	- Make eoi() for clock_event_device optional for x86 where eoi
> > 	is handled in firmware.
> > Changes since v1:
> > 	- Use the correct timer for clocksource on x86
> > 	- Select the correct timer rating for x86
> > 	- Restore freerunning timer behaviour for oneshot event devices
> > 	- Reenable event irq correctly for hotplug
> 
> Sorry for being slow to review this.

No worries, appreciate the review.

> Just a minor nit below.
> 
> > +struct dw_apb_clocksource *
> > +dw_apb_clocksource_init(unsigned rating, char *name, void __iomem *base,
> > +			unsigned long freq)
> > +{
> > +	struct dw_apb_clocksource *dw_cs = kzalloc(sizeof(*dw_cs), GFP_KERNEL);
> > +
> > +	if (!dw_cs)
> > +		return NULL;
> > +
> > +	dw_cs->timer.base = base;
> > +	dw_cs->timer.freq = freq;
> > +	dw_cs->cs.name = name;
> > +	dw_cs->cs.rating = rating;
> > +	dw_cs->cs.read = __apbt_read_clocksource;
> > +	dw_cs->cs.mask = CLOCKSOURCE_MASK(32);
> > +	dw_cs->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS;
> > +	dw_cs->cs.resume = apbt_restart_clocksource;
> > +
> > +	return dw_cs;
> > +}
> 
> So I don't see anything that frees the dw_apb_clocksource structure
> after it has been allocated. Should this instead be allocated by the
> caller and passed in to be initialized here?

Yeah, either that or I could add a dw_apb_clocksource_remove() that does 
the clocksource_unregister() and kfree().  That's probably a little more 
consistent with the rest of the driver.

Jamie
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