On 10/31/2012 04:32 AM, Mike Turquette wrote:

Quoting Stephen Warren (2012-10-30 11:02:05)

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On 10/29/2012 12:32 PM, Mike Turquette wrote:

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Quoting Stephen Warren (2012-10-23 14:45:56)

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What do people think of this? Does it sound like a good idea to go ahead
with a reset subsystem? Should we simply add a new API to the common clock
subsystem instead (and assume that reset and clock domains match 1:1).
Should this be implemented as part of the generic power management domains;
see include/linux/pm_domain.h instead?

Hi Stephen,

I'm not sure a "reset subsystem" is necessary, but I also do not like
using clocks as the keys for IP reset.

I'm not sure what you're suggesting as an alternative to a reset
subsystem (or API if you want something that sounds smaller!) :-)

My point was that I do not know if a new subsystem is necessary or not.
Your suggestion to "simply add a new API to the common clock subsystem"
is an example of an alternative to a whole new subsystem.  However I
instinctively feel that the clock api is not the right place for
reseting devices.

driver/base/power is about the only related place I can think of given a
quick look. However, in a similar way to clocks, I don't think there's
necessarily a 1:1 relationship between power domains and reset domains
either, so driver/base/power doesn't feel like a good fit in just the
same way that drivers/clk doesn't.

I wonder if a drivers/base/reset/ or drivers/base/reset.c would be
appropriate?

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I think it is more common to map IPs to struct device, no?

It is indeed probably common that there's a 1:1 mapping between IP
blocks and struct device. However, I'm sure there are plenty of
counter-examples; IP blocks with multiple reset domains (hence struct
devices that encompass multiple reset domains, or reset domains that
encompass multiple struct devices), just as there are many examples of
non-1:1 mappings between struct device and struct clk.

In OMAP code we handle IP resets through the hwmod code and I prefer
that IP-centric approach to associating IP resets with a clock node.
Perhaps the hwmod approach could serve as inspiration for a new generic
way to reset modules.

OK, I'm not even slightly familiar with the hwmod code, but I keep
hearing about it, so I'll go take a quick look.