[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20140612225553.GO23430@n2100.arm.linux.org.uk>
Date: Thu, 12 Jun 2014 23:55:54 +0100
From: Russell King - ARM Linux <linux@....linux.org.uk>
To: Stephen Warren <swarren@...dotorg.org>
Cc: Peter De Schrijver <pdeschrijver@...dia.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>,
Thierry Reding <thierry.reding@...il.com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-tegra@...r.kernel.org
Subject: Re: [PATCH 0/3] Use Tegra's microsecond counter for udelay()
On Thu, Jun 12, 2014 at 01:38:28PM -0600, Stephen Warren wrote:
> On 06/12/2014 09:58 AM, Peter De Schrijver wrote:
> > This patchset introduces support for Tegra's microsecond counter as the
> > udelay() timer. This is useful on Tegra SoCs which do not have an arch timer
> > such as Tegra20 and Tegra30. Using the microsecond counter instead of a delay
> > based loop avoids potential problems during cpu frequency changes.
> >
> > The set consists of 3 patches:
> >
> > Patch 1 introduces a new call which is used by the ARM architecture delay
> > timer code to prevent changing the delay timer after calibration is finished
> > and thus can be in use.
> >
> > Patch 2 adds logic to choose the delay timer with the highest resolution. This
> > allows the same registration code to be used on all Tegra SoCs and yet use the
> > higher resolution arch timer when available (eg on Tegra114 or Tegra124).
> >
> > Patch 3 adds the actual delay timer code.
> >
> > Patch set has been verified on ventana (Tegra20), beaver (Tegra30),
> > dalmore (Tegra114) and jetson TK1 (Tegra124).
>
> Russell, Paul, do patches 1 and 2 look good to you? If so, if you can
> ack them, I'd be happy to queue this series in the Tegra git tree. If
> that doesn't work for you, please let me know who will apply these
> patches. Thanks.
When I saw them, I did have a question in the back of my mind about
the interlocking - whether we should just mandate that these are
always registered before delay calibration. Then I remember the
mess that platforms made of the sched_clock() stuff.
So, I don't see any other way to ensure that platforms do the right
thing other than providing that kind of stick... so I guess we'll
have to have them.
Acked-by: Russell King <rmk+kernel@....linux.org.uk>
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists