From: Richard Cochran <richardcochran@gmail.com>
To: "Hall, Christopher S" <christopher.s.hall@intel.com>
Cc: "john.stultz@linaro.org" <john.stultz@linaro.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"Kirsher, Jeffrey T" <jeffrey.t.kirsher@intel.com>,
"Ronciak, John" <john.ronciak@intel.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [PATCH v2 4/4] Added getsynctime64() callback
Date: Fri, 14 Aug 2015 08:32:51 +0200 [thread overview]
Message-ID: <20150814063250.GB18603@localhost.localdomain> (raw)
In-Reply-To: <B79D786B7111A34A8CF09F833429C493A90A0E74@ORSMSX109.amr.corp.intel.com>
On Thu, Aug 13, 2015 at 09:10:36PM +0000, Hall, Christopher S wrote:
> > > + if (!cpu_has_art)
> > > + return -EOPNOTSUPP;
> >
> > Perform this check before registration, setting .getsynctime64
> > accordingly.
>
> The problem here is that ART initialization doesn't happen until we
> install TSC as a clocksource. This design is per Thomas'
> suggestion. That occurs after the driver is loaded (as a module).
So that 'cpu_has_art' actually means 'cpu_has_art_and_has_been_initialized'?
In any case, returning EOPNOTSUPP early on, but OK later seems mean to
me. If the clocks aren't ready yet, the error should be EBUSY so that
user space knows it can try again.
Thanks,
Richard
prev parent reply other threads:[~2015-08-14 6:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-07 23:01 [PATCH v2 0/4] Patchset enabling hardware based cross-timestamps for next gen Intel platforms Christopher Hall
2015-08-07 23:01 ` [PATCH v2 1/4] Add generic correlated clocksource code and ART to TSC conversion code Christopher Hall
2015-08-07 23:44 ` Andy Lutomirski
2015-08-07 23:01 ` [PATCH v2 2/4] Add ART initialization code Christopher Hall
2015-08-07 23:01 ` [PATCH v2 3/4] Add support for driver cross-timestamp to PTP_SYS_OFFSET ioctl Christopher Hall
2015-08-10 8:53 ` Richard Cochran
2015-08-07 23:01 ` [PATCH v2 4/4] Added getsynctime64() callback Christopher Hall
2015-08-10 8:49 ` Richard Cochran
2015-08-13 21:10 ` Hall, Christopher S
2015-08-14 6:32 ` Richard Cochran [this message]
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