From: Mark Brown <broonie@kernel.org>
To: Paul Menzel <pmenzel@molgen.mpg.de>
Cc: Bartosz Golaszewski <brgl@kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Liam Girdwood <lgirdwood@gmail.com>,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org, linux-i2c@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] misc: eeprom: at24: Make VCC supply description requirement optional
Date: Sun, 24 May 2026 23:07:23 +0100 [thread overview]
Message-ID: <ahN2m3kCbyTUNXzZ@sirena.org.uk> (raw)
In-Reply-To: <20260524080533.8749-2-pmenzel@molgen.mpg.de>
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On Sun, May 24, 2026 at 10:05:33AM +0200, Paul Menzel wrote:
> Some platforms (e.g. IBM Power System S822LC (8335-GCA POWER8)) do not
> describe the EEPROM’s VCC supply in firmware-provided device trees.
> Using `devm_regulator_get()` on such systems falls back to a dummy
> regulator with a kernel warning:
> Switch to `devm_regulator_get_optional()` and treat -ENODEV as “no
> supply described”. When `vcc_reg` is NULL, skip all
> regulator_enable/disable calls; the hardware is assumed to be always
> powered. Linux now logs:
This is not appropriate unless the device can actually operate without
power, any driver could be used in a system where the firmware does not
describe the regultors and it'd obviously be pointless and error prone
to scatter bodges like this on every single call to a regulator API
function.
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next prev parent reply other threads:[~2026-05-24 22:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-24 8:05 [PATCH] misc: eeprom: at24: Make VCC supply description requirement optional Paul Menzel
2026-05-24 22:07 ` Mark Brown [this message]
2026-05-25 7:07 ` Paul Menzel
2026-05-25 10:32 ` Mark Brown
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