From: olof@lixom•net (Olof Johansson)
To: Arnd Bergmann <arnd@arndb•de>
Cc: linuxppc-dev@ozlabs•org, egor@pasemi•com, paulus@samba•org,
cpufreq@lists•linux.org.uk
Subject: Re: [PATCH v2] [2.6.22] pasemi: cpufreq driver
Date: Thu, 26 Apr 2007 15:26:32 -0500 [thread overview]
Message-ID: <20070426202632.GA17302@lixom.net> (raw)
In-Reply-To: <200704261911.22553.arnd@arndb.de>
On Thu, Apr 26, 2007 at 07:11:21PM +0200, Arnd Bergmann wrote:
> On Thursday 26 April 2007, Olof Johansson wrote:
> > SDC is the system and debug controller, it contains a number of smaller
> > devices such as the PIC, the PMU (Gizmo), RNG, and various debug
> > features. Some already have drivers submitted, others will later on.
>
> Oh well, these chips all seem to be the same. On cell, we have solved
> the problem by introducing the 'cbe_regs' helper library that gives
> access to all those miscellaneous registers to the individual device
> drivers, so that not all of them need to scan the device tree for
> the same registers and map them individually.
Not a bad idea, I'll consider it for the future. Most of our devices are
on a pseudo-PCI bus, so it's only a handful that need special register
access. The stuff in the SDC is the biggest exception.
> The problem with an of_platform_driver for this would be that you
> can only have _one_ driver attached to the registers.
>
> > Unfortunately the setting of the current active state is done to an SDC
> > register, while information of the states is in the PMU, so access to
> > both is needed in the driver.
>
> One thing that you could do is to list only this one register of the
> SDC in the reg property, not all of the SDC.
That doesn't make much sense in this case. The register isn't in the
Gizmo.
Having a driver/library for the SDC that the gizmo driver can use is a
good idea, similar to what you've done on cell. I'll try to have that
ready for 2.6.23, but that shouldn't stop this base driver from going
in now.
-Olof
next prev parent reply other threads:[~2007-04-26 20:26 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-25 20:46 [PATCH] [2.6.22] pasemi: cpufreq driver Olof Johansson
2007-04-25 23:47 ` Arnd Bergmann
2007-04-25 23:57 ` Olof Johansson
2007-04-26 1:57 ` Olof Johansson
2007-04-26 6:56 ` cbe_cpufreq crashes my machine Olof Johansson
2007-04-26 8:39 ` Benjamin Herrenschmidt
2007-04-26 23:07 ` [PATCH] cell: cbe_cpufreq cleanup and crash fix Olof Johansson
2007-04-27 5:22 ` [Cbe-oss-dev] " Akinobu Mita
2007-04-27 5:32 ` Olof Johansson
2007-04-27 5:33 ` [PATCH v2] " Olof Johansson
2007-04-27 7:55 ` Christian Krafft
2007-04-26 5:37 ` [PATCH v2] [2.6.22] pasemi: cpufreq driver Olof Johansson
2007-04-26 8:55 ` Arnd Bergmann
2007-04-26 16:48 ` Olof Johansson
2007-04-26 17:11 ` Arnd Bergmann
2007-04-26 19:05 ` Segher Boessenkool
2007-04-26 20:38 ` Olof Johansson
2007-04-27 0:10 ` Segher Boessenkool
2007-04-26 20:26 ` Olof Johansson [this message]
2007-04-26 20:43 ` Arnd Bergmann
2007-04-26 10:26 ` Johannes Berg
2007-04-26 20:37 ` Olof Johansson
2007-04-27 9:40 ` Johannes Berg
2007-04-27 18:09 ` Olof Johansson
2007-04-27 5:46 ` [PATCH v3] " Olof Johansson
2007-04-29 2:50 ` Dominik Brodowski
2007-04-29 3:40 ` Stephen Rothwell
2007-04-29 4:39 ` Olof Johansson
2007-04-29 4:42 ` Olof Johansson
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