linux-kernel - Re: [PATCH v2 2/6] iio: light: stk3310: Implement vdd supply and power it off during suspend

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Message-ID: <20240428173422.7c0f44cf@jic23-huawei>
Date: Sun, 28 Apr 2024 17:34:22 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Aren Moynihan <aren@...cevolution.org>, Lars-Peter Clausen
 <lars@...afoo.de>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
 <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>,
 Chen-Yu Tsai <wens@...e.org>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Samuel Holland <samuel@...lland.org>, Liam Girdwood <lgirdwood@...il.com>,
 Mark Brown <broonie@...nel.org>, Ondrej Jirman <megi@....cz>, Uwe
 Kleine-König <u.kleine-koenig@...gutronix.de>,
 linux-iio@...r.kernel.org, phone-devel@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev, Willow
 Barraco <contact@...lowbarraco.fr>
Subject: Re: [PATCH v2 2/6] iio: light: stk3310: Implement vdd supply and
 power it off during suspend

On Wed, 24 Apr 2024 02:16:06 +0300
Andy Shevchenko <andy.shevchenko@...il.com> wrote:

> On Wed, Apr 24, 2024 at 1:41 AM Aren Moynihan <aren@...cevolutionorg> wrote:
> >
> > From: Ondrej Jirman <megi@....cz>
> >
> > VDD power input can be used to completely power off the chip during
> > system suspend. Do so if available.  
> 
> ...
> 
> >         ret = stk3310_init(indio_dev);
> >         if (ret < 0)
> > -               return ret;
> > +               goto err_vdd_disable;  
> 
> This is wrong. You will have the regulator being disabled _before_
> IRQ. Note, that the original code likely has a bug which sets states
> before disabling IRQ and removing a handler.
> 
> Side note, you may make the driver neater with help of
> 
>   struct device *dev = &client->dev;
> 
> defined in this patch.
> 
> ...
> 
> >  static int stk3310_suspend(struct device *dev)
> >  {
> >         struct stk3310_data *data;  
> 
> >         data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));  
> 
> Side note: This may be updated (in a separate change) to use
> dev_get_drvdata() directly.
> 
> Jonathan, do we have something like iio_priv_from_drvdata(struct
> device *dev)? Seems many drivers may utilise it.

Not yet, but I'm not sure it's a good idea as there is no inherent
reason to assume the drvdata is a struct iio_dev.  It often is but
adding a function that assumes that is a path to subtle bugs.

Jonathan

> 
> >  }  
> 
> ...
> 
> >  static int stk3310_resume(struct device *dev)  
> 
> Ditto.
> 
> --
> With Best Regards,
> Andy Shevchenko