On Tue, Jan 26, 2021 at 08:15:35AM +0000, Lee Jones wrote:

On Mon, 25 Jan 2021, Cristian Ciocaltea wrote:

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Hi Lee,

On Mon, Jan 25, 2021 at 02:25:58PM +0000, Lee Jones wrote:

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On Wed, 20 Jan 2021, Cristian Ciocaltea wrote:

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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.

 
[...]

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+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.

Right, but would this be helpful to any non-Actions drivers?

If so, perhaps it should reside as a Regmap helper?

I got it now, thanks for the suggestion. As a matter of fact this was
my initial intention, but since I was not aware of any other use case
I decided to keep it private for the moment.

Most probably this hardware design is not specific to Actions only, so
it might be helpful to other drivers as well. Therefore I am going to
reconsider this and if/when it is accepted upstream, I will come back
with a separate update patch for this driver.

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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.

That's fine.

Please re-submit the patches which have not been applied already.

I have just submitted v7 with the two patches dropped.

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  Acked-for-MFD-by: Lee Jones [off-list ref]

Thanks,
Cristi

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
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