[lkml]   [2015]   [Jun]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [RFC][PATCH] regmap: make REGCACHE_NONE maps return error on regcache_sync
On Fri, May 08, 2015 at 11:34:54AM +0100, Nariman Poushin wrote:
> On Fri, May 08, 2015 at 11:20:19AM +0100, Mark Brown wrote:
> > On Fri, May 08, 2015 at 10:55:37AM +0100, Nariman Poushin wrote:
> > > Signed-off-by: Nariman Poushin <>
> > > ---
> > > regcache currently causes a BUG_ON if cache_sync/sync_region is
> > > called on a map with cache_type REGCACHE_NONE. This is not
> > > consistent with the behaviour of regcache_read/write which
> > > currently just return -ENOSYS and only throws a BUG_ON if
> > > the cache_type is something that _should_ have cache ops,
> > > but doesn't. Sure your device might not work, it but doesn't
> > > seem right to panic the kernel. The other option I suppose
> > > is to change it to a WARN_ON.
> >
> > Please submit patches in the format covered in SubmittingPatches, the
> > changelog goes before the signoff.
> >
> Will do, apologies.
> > The reason this is so loud is that while it's reasonable that generic
> > code could end up triggering a write it's difficult to see any way in
> > which a sync could be triggered on a device without a cache without it
> > being an obvious bug. Since people frequently don't bother checking
> > return codes loud log messages are our only real way of reporting this,
> > given where syncs tend to happen it's not likely to happen in an obscure
> > code path that won't get seen.
> Fair enough, that makes sense.

In light of this:

Would it be prudent to now make these WARN_ON? It seems like it's not
worth taking the kernel down in the case where you are trying to sync to
a non-existent cache for a peripheral. Of course it could be that the
particular write _not_ going in to the cache is catastrophic for some
other reason, but it still seems a bit severe and given the discussion
above not the intended usage for BUG_ON. It doesn't feel like this
satisfies the test:

"The *ONLY* acceptable reason for a BUG_ON() is if the machine is dead
anyway because of some major internal corruption."

Anyway, just a thought. Not sure if this constitutes a "content-less
bump", I just read something that I thought may change our previous
assumptions, if it does, apologies.

> Thanks
> Nariman
> _______________________________________________
> patches mailing list

 \ /
  Last update: 2015-06-08 16:41    [W:0.074 / U:0.260 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site