[PATCH v3] ARM: sched_clock: allow sched_clock to be selected at runtime

[PATCH v3] ARM: sched_clock: allow sched_clock to be selected at runtime

[Marc Zyngier]

sched_clock() is yet another blocker on the road to the single
image. This patch implements an idea by Russell King:

http://www.spinics.net/lists/linux-omap/msg49561.html

Instead of asking the platform to implement both sched_clock()
itself and the rollover callback, simply register a read()
function, and let the ARM code care about sched_clock() itself,
the conversion to ns and the rollover. sched_clock() uses
this read() function as an indirection to the platform code.

This allow some simplifications and possibly some footprint gain
when multiple platforms are compiled in. Among the drawbacks,
the removal of the *_fixed_sched_clock optimization which could
negatively impact some platforms (sa1100, tegra, versatile
and omap).

Tested on 11MPCore, OMAP4 and Tegra.

Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: Krzysztof Halasa <khc@pm.waw.pl>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Colin Cross <ccross@android.com>
Cc: Erik Gilling <konkers@android.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Alessandro Rubini <rubini@unipv.it>
Cc: STEricsson <STEricsson_nomadik_linux@list.st.com>
Cc: Lennert Buytenhek <kernel@wantstofly.org>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Tested-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
Based on 3.1-rc4.

[PATCH v3] ARM: sched_clock: allow sched_clock to be selected at runtime

[Tony Lindgren]

* Marc Zyngier <marc.zyngier@arm.com> [110830 16:29]:
> sched_clock() is yet another blocker on the road to the single
> image. This patch implements an idea by Russell King:
> 
> http://www.spinics.net/lists/linux-omap/msg49561.html
> 
> Instead of asking the platform to implement both sched_clock()
> itself and the rollover callback, simply register a read()
> function, and let the ARM code care about sched_clock() itself,
> the conversion to ns and the rollover. sched_clock() uses
> this read() function as an indirection to the platform code.
> 
> This allow some simplifications and possibly some footprint gain
> when multiple platforms are compiled in. Among the drawbacks,
> the removal of the *_fixed_sched_clock optimization which could
> negatively impact some platforms (sa1100, tegra, versatile
> and omap).
> 
> Tested on 11MPCore, OMAP4 and Tegra.

Great, seems to boot just fine with printk_time :)

I gave it a quick boot test on omap16xx, 2420, 3430,
3630 and 4430:

Tested-by: Tony Lindgren <tony@atomide.com>

[PATCH v3] ARM: sched_clock: allow sched_clock to be selected at runtime

[Marc Zyngier]

Hi Tony,

On 02/09/11 13:49, Tony Lindgren wrote:
> * Marc Zyngier <marc.zyngier@arm.com> [110830 16:29]:
>> sched_clock() is yet another blocker on the road to the single
>> image. This patch implements an idea by Russell King:
>>
>> http://www.spinics.net/lists/linux-omap/msg49561.html
>>
>> Instead of asking the platform to implement both sched_clock()
>> itself and the rollover callback, simply register a read()
>> function, and let the ARM code care about sched_clock() itself,
>> the conversion to ns and the rollover. sched_clock() uses
>> this read() function as an indirection to the platform code.
>>
>> This allow some simplifications and possibly some footprint gain
>> when multiple platforms are compiled in. Among the drawbacks,
>> the removal of the *_fixed_sched_clock optimization which could
>> negatively impact some platforms (sa1100, tegra, versatile
>> and omap).
>>
>> Tested on 11MPCore, OMAP4 and Tegra.
> 
> Great, seems to boot just fine with printk_time :)
> 
> I gave it a quick boot test on omap16xx, 2420, 3430,
> 3630 and 4430:
> 
> Tested-by: Tony Lindgren <tony@atomide.com>

Thanks for testing!.

	M.
-- 
Jazz is not dead. It just smells funny...