[i2c] [PATCH] i2c: Deprecate legacy RTC drivers

[James Chapman]

Hi Dave,

I've already acked Jean's patch.

I'm waiting for the board vendor to test a ppc7d patch that removes the 
use of the rtc hooks and switches over to rtc-ds1307 as you describe. 
I'll submit it to the ppc maintainers once the board vendor has verified it.

-- 
James Chapman
Katalix Systems Ltd
http://www.katalix.com
Catalysts for your Embedded Linux software development

David Brownell wrote:
>> Regarding the ds1337 driver, it exports a public function,
>> ds1337_do_command(), which is currently used by functions in
>> arch/ppc/platforms/radstone_ppc7d.c. This code is used to provide
>> implementations used by the ppc arch get_rtc_time() and set_rtc_time()
>> platform hooks.
> 
> The RTC framework has CONFIG_RTC_HCTOSYS and CONFIG_RTC_HCTOSYS_DEVICE
> which ought to suffice for everything except NTP integration.
> 
> By the way:  I notice that ppc7d_{get,set}_rtc_time() call that
> hook while holding a spinlock ... not allowed, I'm surprised
> such a bug has persisted for about two years now!  Maybe part
> of the issue is lockdep not working yet on Powerpc/PPC?
> 
> 
>> If the rtc subsystem now provides a better way to hook 
>> up these functions, the radstone_ppc7d code could be changed to use it
>> instead of ds1337_do_command(), thereby allowing the old ds1337 driver
>> to be removed.
> 
> I think there was some noise afoot to switch all of PPC over
> to the new RTC framework once the resume hooks were merged;
> and that's achieved by 2.6.22-rc1 ... I figure that conversion
> will need to happen one driver at a time.
> 
> 
>> Perhaps the radstone_ppc7d platform code should use rtc_read_time() and
>> rtc_set_time() instead? Is it possible for platform code to obtain the
>> rtc's struct class_device which are needed by those calls?
> 
> More like:  the PPC7D stuff should stop using the ppc_md RTC hooks,
> and just update its default config to use the RTC framework with
> CONFIG_RTC_HCTOSYS.
> 
> In fact, since I've got patches to switch rtc-ds1307 over to a
> new-style I2C driver, I'll send you a patch to test that on that
> platform as soon as I re-verify those on the 2.6.22-rc1 kernel.
> 
> - Dave
>