Re: [PATCH v6 3/7] mfd: Add MFD driver for ATC260x PMICs

Cristian Ciocaltea
2021-01-26T09:22:51Z

Hi Lee,

On Mon, Jan 25, 2021 at 02:25:58PM +0000, Lee Jones wrote:
> On Wed, 20 Jan 2021, Cristian Ciocaltea wrote:
>
> > Add initial support for the Actions Semi ATC260x PMICs which integrates
> > Audio Codec, Power management, Clock generation and GPIO controller
> > blocks.
> >
> > For the moment this driver only supports Regulator, Poweroff and Onkey
> > functionalities for the ATC2603C and ATC2609A chip variants.

[...]

> > +static void regmap_lock_mutex(void *__mutex)
> > +{
> > + struct mutex *mutex = __mutex;
> > +
> > + /*
> > + * Using regmap within an atomic context (e.g. accessing a PMIC when
> > + * powering system down) is normally allowed only if the regmap type
> > + * is MMIO and the regcache type is either REGCACHE_NONE or
> > + * REGCACHE_FLAT. For slow buses like I2C and SPI, the regmap is
> > + * internally protected by a mutex which is acquired non-atomically.
> > + *
> > + * Let's improve this by using a customized locking scheme inspired
> > + * from I2C atomic transfer. See i2c_in_atomic_xfer_mode() for a
> > + * starting point.
> > + */
> > + if (system_state > SYSTEM_RUNNING && irqs_disabled())
> > + mutex_trylock(mutex);
> > + else
> > + mutex_lock(mutex);
> > +}
>
> Would this be useful to anyone else?

If you refer to the locking scheme, it is currently required by the
power-off driver to handle atomic contexts.

> For my own reference (apply this as-is to your sign-off block):

Please note the patches "[4/7] regulator: ..." and "[5/7] power: ..."
have been already picked up by Mark and Sebastian, respectively, while
Dmitry suggested to merge "[6/7] input: ..." through MFD.

> Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>
>
> --
> Lee Jones [李琼斯]
> Senior Technical Lead - Developer Services
> Linaro.org │ Open source software for Arm SoCs
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Thanks,
Cristi