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Date:   Mon, 20 Jun 2022 16:05:54 +0100
From:   Mark Brown <broonie@kernel.org>
To:     Dong Aisheng <aisheng.dong@nxp.com>
Cc:     linux-kernel@vger.kernel.org, dongas86@gmail.com,
        l.stach@pengutronix.de, peng.fan@nxp.com, shawnguo@kernel.org
Subject: Re: [PATCH RFC 1/2] regmap: add option to disable debugfs
Message-ID: <YrCM0reni+x/KWsG@sirena.org.uk>
References: <20220620134758.1286480-1-aisheng.dong@nxp.com>
 <20220620134758.1286480-2-aisheng.dong@nxp.com>
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On Mon, Jun 20, 2022 at 09:47:57PM +0800, Dong Aisheng wrote:
> The regmap core will create debugfs by default for each instance.
> However, it's fairly possible that some devices may not work properly
> with regmap registers dump via debugfs due to it may be in suspend
> state (e.g. Power domain is off).
>=20
> Current regmap core does not support runtime pm for MMIO bus.
> Although there have been several retries [1] in community but finally
> didn't get accepted.
>=20
> This patch adds an option to allow drivers to claim no debugfs support
> due to possible platform limitations.
>=20
> 1. Link: https://lkml.iu.edu/hypermail/linux/kernel/1204.0/01646.html

As indicated in the message you're linking to here if the device can't
be accessed it should be being put in cache only mode which will ensure
that nothing can do any physical accesses.

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