linux-kernel - Re: [PATCH 1/2] regmap: teach regmap to use raw spinlocks if requested in the config

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Message-ID: <YSzSQzDuWcrzSPtR@sirena.org.uk>
Date:   Mon, 30 Aug 2021 13:42:43 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Vladimir Oltean <vladimir.oltean@....com>,
        Lee Jones <lee.jones@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, Marc Zyngier <maz@...nel.org>,
        Hou Zhiqiang <Zhiqiang.Hou@....com>,
        Biwen Li <biwen.li@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] regmap: teach regmap to use raw spinlocks if
 requested in the config

On Mon, Aug 30, 2021 at 01:02:33PM +0200, Rasmus Villemoes wrote:

> i.e. the regmap code can actually do allocations under whatever internal
> lock it uses. So ISTM that any regmap that uses a raw_spinlock (whether
> unconditionally or via Vladimir's opt-in) cannot be used with
> regmap_bulk_write().

No, anything that's using a spinlock already needs to avoid any
allocations - ensuring that either there's no cache or that the
cache is fully initialized with defaults.  The only non-cache
allocations that might be done are only used by buses that sleep
anyway.

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