Re: [PATCH v8 9/9] iio: accel: mma8452: Support interrupt sharing

[Joshua Crofts]

On Mon, 07 Sep 2026 16:51:04 +0200
Esben Haabendal <esben@xxxxxxxxxx> wrote:

> Adding support for sharing interrupt line with other device requires the
> interrupt handler to handle runtime PM suspension properly, ignoring the
> irq if the device is suspended (maybe even off). And while at it, we use
> the PM reference to ensure we do not get suspended while processing an irq.
> 
> In order to prevent the chip from raising irq while suspended (that is when
> using fixed regulator, where suspend just means setting the device in
> STANDBY mode), we disable all interrupt sources by clearing CTRL_REG4, and
> then restores the value again when resuming.
> 
> With that in place, it is safe to add the IRQF_SHARED flag.
> 
> Keep in mind that the device by default is using push-pull for the irq pin,
> which might require additional hardware design to allow interrupt sharing.
> 
> Signed-off-by: Esben Haabendal <esben@xxxxxxxxxx>
> ---

...

> @@ -1784,29 +1796,62 @@ static void mma8452_remove(struct i2c_client *client)
>  #ifdef CONFIG_PM
>  static int mma8452_runtime_suspend(struct device *dev)
>  {
> -	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
>  	struct mma8452_data *data = iio_priv(indio_dev);
>  	int ret;
>  
> -	scoped_guard(mutex, &data->lock)
> -		ret = mma8452_standby(data);
> +	guard(mutex)(&data->lock);
> +

Hmm, this patch might benefit from breaking it into multiple patches
(the change from scoped_guard to guard, the local pointers etc. along
the fact that these aren't mentioned in the commit message), but
that's up to Jonathan.


-- 
Kind regards,
Joshua Crofts