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From: Vladimir Oltean <olteanv@gmail.com>
To: Kurt Kanzenbach <kurt@linutronix.de>
Cc: Andrew Lunn <andrew@lunn.ch>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	netdev@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
	devicetree@vger.kernel.org,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Richard Cochran <richardcochran@gmail.com>,
	Kamil Alkhouri <kamil.alkhouri@hs-offenburg.de>,
	ilias.apalodimas@linaro.org
Subject: Re: [PATCH v3 5/8] net: dsa: hellcreek: Add TAPRIO offloading support
Date: Tue, 25 Aug 2020 12:38:30 +0300	[thread overview]
Message-ID: <20200825093830.r2zlpowtmhgwm6rz@skbuf> (raw)
In-Reply-To: <878se3133y.fsf@kurt>

On Tue, Aug 25, 2020 at 11:33:53AM +0200, Kurt Kanzenbach wrote:
> On Tue Aug 25 2020, Vladimir Oltean wrote:
> > On Thu, Aug 20, 2020 at 10:11:15AM +0200, Kurt Kanzenbach wrote:
> >
> > Explain again how this works, please? The hrtimer measures the CLOCK_TAI
> > of the CPU, but you are offloading the CLOCK_TAI domain of the NIC? So
> > you are assuming that the CPU and the NIC PHC are synchronized? What if
> > they aren't?
> 
> Yes, I assume that's synchronized with e.g. phc2sys.
> 

My intuition tells me that this isn't the user's expectation, and that
it should do the right thing even if it's not synchronized to the system
clock.

> >
> > And what if the base-time is in the past, do you deal with that (how
> > does the hardware deal with a base-time in the past)?
> > A base-time in the past (example: 0) should work: you should advance the
> > base-time into the nearest future multiple of the cycle-time, to at
> > least preserve phase correctness of the schedule.
> 
> If the hrtimer is programmed with a value in the past, it fires
> instantly.

Yes, it does.

> The callback is executed and the start time is programmed.
> 

With a valid value from the hardware's perspective?

Thanks,
-Vladimir

  reply	other threads:[~2020-08-25  9:38 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-20  8:11 [PATCH v3 0/8] Hirschmann Hellcreek DSA driver Kurt Kanzenbach
2020-08-20  8:11 ` [PATCH v3 1/8] net: dsa: Add tag handling for Hirschmann Hellcreek switches Kurt Kanzenbach
2020-08-20  8:11 ` [PATCH v3 2/8] net: dsa: Add DSA driver " Kurt Kanzenbach
2020-08-24 22:44   ` Andrew Lunn
2020-08-25  9:07     ` Kurt Kanzenbach
2020-08-25 13:56       ` Andrew Lunn
2020-08-25 14:48         ` Kurt Kanzenbach
2020-08-27 10:29           ` Kurt Kanzenbach
2020-08-20  8:11 ` [PATCH v3 3/8] net: dsa: hellcreek: Add PTP clock support Kurt Kanzenbach
2020-08-20  8:11 ` [PATCH v3 4/8] net: dsa: hellcreek: Add support for hardware timestamping Kurt Kanzenbach
2020-08-20  8:11 ` [PATCH v3 5/8] net: dsa: hellcreek: Add TAPRIO offloading support Kurt Kanzenbach
2020-08-22 14:39   ` Vladimir Oltean
2020-08-24  6:10     ` Kurt Kanzenbach
2020-08-24 23:45       ` Vinicius Costa Gomes
2020-08-25  9:42         ` Kurt Kanzenbach
2020-08-25 17:58           ` Vinicius Costa Gomes
2020-08-27 10:12             ` Kurt Kanzenbach
2020-08-25  9:46         ` Vladimir Oltean
2020-08-25 10:09           ` Kurt Kanzenbach
2020-08-25 17:33           ` Vinicius Costa Gomes
2020-08-24 22:56   ` Vladimir Oltean
2020-08-25  9:33     ` Kurt Kanzenbach
2020-08-25  9:38       ` Vladimir Oltean [this message]
2020-08-25  9:55         ` Kurt Kanzenbach
2020-08-27 16:25           ` Richard Cochran
2020-08-28 12:31             ` Kurt Kanzenbach
2020-08-24 23:57   ` Vinicius Costa Gomes
2020-08-25  9:23     ` Kurt Kanzenbach
2020-08-25  9:32       ` Vladimir Oltean
2020-09-01 14:20         ` Kurt Kanzenbach
2020-09-01 14:47           ` Vladimir Oltean
2020-08-25 17:50       ` Vinicius Costa Gomes
2020-08-20  8:11 ` [PATCH v3 6/8] net: dsa: hellcreek: Add PTP status LEDs Kurt Kanzenbach
2020-08-24 22:50   ` Andrew Lunn
2020-08-20  8:11 ` [PATCH v3 7/8] dt-bindings: Add vendor prefix for Hirschmann Kurt Kanzenbach
2020-08-20  8:11 ` [PATCH v3 8/8] dt-bindings: net: dsa: Add documentation for Hellcreek switches Kurt Kanzenbach
2020-08-24 22:52   ` Andrew Lunn
2020-08-25 22:28   ` Rob Herring
2020-08-24 21:31 ` [PATCH v3 0/8] Hirschmann Hellcreek DSA driver Jakub Kicinski
2020-08-24 22:02   ` Vladimir Oltean
2020-08-24 22:35     ` David Miller
2020-08-24 22:57       ` Vladimir Oltean
2020-08-25 11:21       ` Kurt Kanzenbach
2020-08-25 17:14         ` Florian Fainelli

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