From:   Alexander Stein <alexander.stein@ew.tq-group.com>
To:     Mark Brown <broonie@kernel.org>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] regmap: cache: Do not panic for REGCACHE_NONE regmap
Date:   Fri, 10 Mar 2023 14:35:13 +0100
Message-ID: <2399331.NgBsaNRSFp@steina-w>
Organization: TQ-Systems GmbH
In-Reply-To: <ZAsqVf8/C3lHOF8W@sirena.org.uk>
References: <20230310073911.3470892-1-alexander.stein@ew.tq-group.com> <ZAsqVf8/C3lHOF8W@sirena.org.uk>
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Hi Mark,

Am Freitag, 10. M=E4rz 2023, 14:02:13 CET schrieb Mark Brown:
> * PGP Signed by an unknown key
>=20
> On Fri, Mar 10, 2023 at 08:39:10AM +0100, Alexander Stein wrote:
> > Most regcache operations do check for REGCACHE_NONE, before ensuring
> > doing BUG_ON(!map->cache_ops). The missing regcache_sync* functions
> > panic on REGCACHE_NONE regmaps instead. Add an early return for non-cac=
hed
> > ones.
>=20
> Why would we be trying to do a regcache_sync() on a device with
> no cache?

Indeed, that makes no sense. That's indicating a bug in a driver, but why d=
o=20
we need to panic the kernel in this case?
On the other hand the same question applies to other regcache related=20
functions currently checking for non-cached maps. There is no common=20
behaviour:

panic:
* regcache_sync
* regcache_sync_region

returning -EINVAL:
* regcache_drop_region

returning -ENOSYS:
* regcache_read

returning success (0):
* regcache_write

early return (void return value):
* regcache_exit

Given all these possibilities I have no idea what's the right thing to do.

Best regards,
Alexander

=2D-=20
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