Messages in this thread | | | Date | Thu, 25 Jun 2015 15:49:48 +0100 | From | Mark Brown <> | Subject | Re: [RFC PATCH 1/2] regmap: add configurable lock class key for lockdep |
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On Thu, Jun 25, 2015 at 05:35:03PM +0800, Nicolas Boichat wrote:
> I'm trying to revive Antti's patch [1], as we are hitting similar issue > with rt5677 driver. I only updated the commit message and documentation, > I kept both Signed-off-by and From lines, with a small note highlighting > my changes, let me know if that's not appropriate.
This continues to have the same problems as the previous version of the patch where I can't really tell how users are supposed to figure out if they should use this or not. There will be cases where there is a clear use within the driver itself but as far as I can tell almost any driver might be bitten by this if some underlying driver on a given system happens to use a regmap so should be allocating a class.
> One issue that was raised by Mark at the time is that a per-regmap_config > lock class might not be enough (Mark mentioned clocks as an example). The > current implementation should be good enough as long as the clock regmaps > do not access each other. If this is a problem, maybe we should consider > replacing lockdep_lock_class_key by a boolean use_own_lock_class that would > allocate/use a per regmap instance lock class, or have devm_regmap_init > take an extra parameter specifying the lock class.
I think this is a problem and making this something that every regmap does by default was my original suggestion, there's also Arjan's suggestion of just using nested mutexes rather than classes. [unhandled content-type:application/pgp-signature] | |