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From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@suse.de>,
	Ashok Raj <ashok.raj@intel.com>,
	Andi Kleen <andi.kleen@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	Ricardo Neri <ricardo.neri@intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Tony Luck <tony.luck@intel.com>,
	Clemens Ladisch <clemens@ladisch.de>,
	Arnd Bergmann <arnd@arndb.de>,
	Philippe Ombredanne <pombredanne@nexb.com>,
	Kate Stewart <kstewart@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [RFC PATCH v2 03/14] x86/hpet: Calculate ticks-per-second in a separate function
Date: Mon, 8 Apr 2019 19:04:05 -0700	[thread overview]
Message-ID: <20190409020405.GA7070@ranerica-svr.sc.intel.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1903262201140.1789@nanos.tec.linutronix.de>

On Tue, Mar 26, 2019 at 10:03:02PM +0100, Thomas Gleixner wrote:
> On Wed, 27 Feb 2019, Ricardo Neri wrote:
> >  int hpet_alloc(struct hpet_data *hdp)
> >  {
> >  	u64 cap, mcfg;
> > @@ -845,7 +868,6 @@ int hpet_alloc(struct hpet_data *hdp)
> >  	size_t siz;
> >  	struct hpet __iomem *hpet;
> >  	static struct hpets *last;
> > -	unsigned long period;
> >  	unsigned long long temp;
> >  	u32 remainder;
> >  
> > @@ -881,6 +903,8 @@ int hpet_alloc(struct hpet_data *hdp)
> >  
> >  	cap = readq(&hpet->hpet_cap);
> >  
> > +	temp = hpet_get_ticks_per_sec(cap);
> 
> Just putting stuff to random places does not make the code any better.

This seems to not be needed. I'll remove it and directly save the result
in hpetp->hp_tick_freq;

> 
> >  	ntimer = ((cap & HPET_NUM_TIM_CAP_MASK) >> HPET_NUM_TIM_CAP_SHIFT) + 1;
> >  
> >  	if (hpetp->hp_ntimer != ntimer) {
> > @@ -897,11 +921,6 @@ int hpet_alloc(struct hpet_data *hdp)
> >  
> >  	last = hpetp;
> >  
> > -	period = (cap & HPET_COUNTER_CLK_PERIOD_MASK) >>
> > -		HPET_COUNTER_CLK_PERIOD_SHIFT; /* fs, 10^-15 */
> > -	temp = 1000000000000000uLL; /* 10^15 femtoseconds per second */
> > -	temp += period >> 1; /* round */
> > -	do_div(temp, period);
> >  	hpetp->hp_tick_freq = temp; /* ticks per second */
> 
> What's wrong with the obvious:
> 
>        hpetp->hp_tick_freq = hpet_get_ticks_per_sec(cap);
> 
> Hmm?

Nothing wrong. I'll implement this change.

Thanks and BR,
Ricardo

  reply	other threads:[~2019-04-09  2:05 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-27 16:05 [RFC PATCH v2 00/14] Implement an HPET-based hardlockup detector Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 01/14] x86/msi: Add definition for NMI delivery mode Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 02/14] x86/hpet: Expose more functions to read and write registers Ricardo Neri
2019-03-26 21:00   ` Thomas Gleixner
2019-04-09  2:03     ` Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 03/14] x86/hpet: Calculate ticks-per-second in a separate function Ricardo Neri
2019-03-26 21:03   ` Thomas Gleixner
2019-04-09  2:04     ` Ricardo Neri [this message]
2019-02-27 16:05 ` [RFC PATCH v2 04/14] x86/hpet: Reserve timer for the HPET hardlockup detector Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 05/14] x86/hpet: Relocate flag definitions to a header file Ricardo Neri
2019-03-26 21:11   ` Thomas Gleixner
2019-04-09  2:04     ` Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 06/14] x86/hpet: Configure the timer used by the hardlockup detector Ricardo Neri
2019-03-26 21:13   ` Thomas Gleixner
2019-04-09  2:04     ` Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 07/14] watchdog/hardlockup: Define a generic function to detect hardlockups Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 08/14] watchdog/hardlockup: Decouple the hardlockup detector from perf Ricardo Neri
2019-03-26 21:18   ` Thomas Gleixner
2019-04-09  2:05     ` Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 09/14] watchdog/hardlockup: Make arch_touch_nmi_watchdog() to hpet-based implementation Ricardo Neri
2019-02-27 16:17   ` Paul E. McKenney
2019-03-01  1:17     ` Ricardo Neri
2019-03-26 21:20       ` Thomas Gleixner
2019-04-09  2:05         ` Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 10/14] kernel/watchdog: Add a function to obtain the watchdog_allowed_mask Ricardo Neri
2019-03-26 21:22   ` Thomas Gleixner
2019-04-09  2:05     ` Ricardo Neri
2019-04-09 11:34   ` Peter Zijlstra
2019-04-11  1:15     ` Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 11/14] x86/watchdog/hardlockup: Add an HPET-based hardlockup detector Ricardo Neri
2019-03-26 20:49   ` Thomas Gleixner
2019-04-09  2:02     ` Ricardo Neri
2019-04-09 10:59     ` Peter Zijlstra
2019-04-10  1:13       ` Ricardo Neri
2019-04-05 16:12   ` Suthikulpanit, Suravee
2019-04-09  2:14     ` Ricardo Neri
2019-04-09 11:03   ` Peter Zijlstra
2019-04-10  1:05     ` Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 12/14] x86/watchdog/hardlockup/hpet: Determine if HPET timer caused NMI Ricardo Neri
2019-03-26 20:55   ` Thomas Gleixner
2019-04-09  2:02     ` Ricardo Neri
2019-04-09 11:28   ` Peter Zijlstra
2019-04-10  1:19     ` Ricardo Neri
2019-04-10  7:01       ` Peter Zijlstra
2019-04-11  1:12         ` Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 13/14] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter Ricardo Neri
2019-03-26 21:29   ` Thomas Gleixner
2019-04-09  2:07     ` Ricardo Neri
2019-02-27 16:05 ` [RFC PATCH v2 14/14] x86/watchdog: Add a shim hardlockup detector Ricardo Neri

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