Messages in this thread | | | From | Alexander Stein <> | Subject | Re: [PATCH 1/1] regmap: regcache-rbtree: Use GFP_ATOMIC when using spinlocks | Date | Tue, 21 Jul 2015 08:14:32 +0200 |
| |
On Monday 20 July 2015 18:26:27, Mark Brown wrote: > > AFAICS even a flat cache seems also only be usefull when providing > > defaults, no? (Or having volatile registers). > > Well, it's *better* to provide defaults since otherwise everything > defaults to 0 but it does avoid the whole allocation during fast path > issue since it allocates the cache on init and perhaps that's OK.
There is another reason for using REGCACHE_FLAT: Using regcache_cache_only (e.g. during suspend) which is not possible with REGCACHE_NONE.
> > So how to handle this properly? Bail out, if fast_io is available and > > cache_type != (REGCACHE_NONE || REGCACHE_FLAT)? > > Or perhaps just if we have to do an allocation? I can see that someone > might want to use an rbtree and would be careful enough to do the init, > though I *am* a bit dubious about it.
I'm feeling uncomfortable this warning occured only when (at least) CONFIG_LOCKDEP is enabled. It warns right ahead but only if you begged for it... Even if defaults are provided an extension to the register set (e.g. a more recent IP revision with more features) might not be synchronized with the defaults. Nobody might noticed until CONFIG_LOCKDEP is enabled and the register without defaults gets written.
Best regards, Alexander -- Dipl.-Inf. Alexander Stein SYS TEC electronic GmbH alexander.stein@systec-electronic.com
Legal and Commercial Address: Am Windrad 2 08468 Heinsdorfergrund Germany
Office: +49 (0) 3765 38600-0 Fax: +49 (0) 3765 38600-4100
Managing Directors: Director Technology/CEO: Dipl.-Phys. Siegmar Schmidt; Director Commercial Affairs/COO: Dipl. Ing. (FH) Armin von Collrepp Commercial Registry: Amtsgericht Chemnitz, HRB 28082; USt.-Id Nr. DE150534010
| |