linux-kernel - Re: [PATCH v4 2/3] iio: light: Add support for vishay vcnl4035

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Date:   Fri, 3 Aug 2018 21:55:29 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Parthiban Nallathambi <pn@...x.de>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald <pmeerw@...erw.net>,
        Rob Herring <robh+dt@...nel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>,
        devicetree <devicetree@...r.kernel.org>,
        Matthias Brugger <matthias.bgg@...il.com>, wd@...x.de,
        sbabic@...x.de, Heiko Schocher <hs@...x.de>
Subject: Re: [PATCH v4 2/3] iio: light: Add support for vishay vcnl4035

On Thu, 2 Aug 2018 22:34:14 +0300
Andy Shevchenko <andy.shevchenko@...il.com> wrote:

> On Thu, Aug 2, 2018 at 9:27 PM, Parthiban Nallathambi <pn@...x.de> wrote:
> > Add support for VCNL4035, which is capable of Ambient light
> > sensing (ALS) and proximity function. This patch adds support
> > only for ALS function  
> 
> > +#include <linux/module.h>
> > +#include <linux/i2c.h>
> > +#include <linux/bitops.h>
> > +#include <linux/regmap.h>
> > +#include <linux/pm_runtime.h>  
> 
> Sort?
> 
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/sysfs.h>
> > +#include <linux/iio/events.h>
> > +#include <linux/iio/buffer.h>
> > +#include <linux/iio/trigger.h>
> > +#include <linux/iio/trigger_consumer.h>
> > +#include <linux/iio/triggered_buffer.h>  
> 
> Ditto.
> 
> > +       if (reg & (VCNL4035_INT_ALS_IF_H_MASK | VCNL4035_INT_ALS_IF_L_MASK))
> > +               return true;
> > +       else
> > +               return false;  
> 
> return !!(reg & ...); ?
> 
> > +static irqreturn_t vcnl4035_drdy_irq_thread(int irq, void *private)
> > +{
> > +       struct iio_dev *indio_dev = private;
> > +       struct vcnl4035_data *data = iio_priv(indio_dev);
> > +  
> 
> > +       if (vcnl4035_is_triggered(data)) {  
> 
> Here is negative conditional suits.
> 
> > +#ifndef CONFIG_PM  
> 
> Why?
> 
> > +       ret = vcnl4035_set_als_power_state(data, VCNL4035_MODE_ALS_ENABLE);
> > +       if (ret < 0)
> > +               return ret;
> > +#endif  
> 
> > +               pr_err("regmap_write default THDH returned %d\n", ret);  
> 
> dev_err()
> 
> > +               pr_err("regmap_write default THDL returned %d\n", ret);  
> 
> Ditto.
> 
> 
> > +       ret = pm_runtime_set_active(&client->dev);
> > +       if (ret < 0)
> > +               goto fail_poweroff;
> > +
> > +       pm_runtime_enable(&client->dev);
> > +       pm_runtime_set_autosuspend_delay(&client->dev, VCNL4035_SLEEP_DELAY_MS);
> > +       pm_runtime_use_autosuspend(&client->dev);  
> 
> Usually we do this after we probed the device.
I'm not sure we should.  The docs are fairly clear on this:

"In order to use autosuspend, subsystems or drivers must call
pm_runtime_use_autosuspend() (preferably before registering the device), and
thereafter they should use the various *_autosuspend() helper functions instead
of the non-autosuspend counterparts:" (Documentation/runtime_pm.txt)

It also makes more logical sense to have removed the userspace interfaces before
unwinding this as then we don't have annoying races around the inevitable
set_suspended.

> 
> > +       if (client->irq) {  
> 
> First of all, it can be negative.
> Second, care to factor out this rather long branch to a separate function?
> 
> > +               if (ret < 0) {
> > +                       dev_err(&client->dev, "request irq %d for trigger0 failed\n",
> > +                               client->irq);
> > +                       goto fail_buffer_clean;
> > +                       }  
> 
> Indentation.
> 
> > +       }  
> 
> So, do I understand correctly that IRQ is optional for this device?
> 
> 
> 
> > +#ifdef CONFIG_PM
> > +static int vcnl4035_runtime_suspend(struct device *dev)  
> 
> Perhaps __maybe_unused
> 
> > +static int vcnl4035_runtime_resume(struct device *dev)  
> 
> Ditto.
> 
> > +{
> > +       struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> > +       struct vcnl4035_data *data = iio_priv(indio_dev);
> > +       int ret;
> > +
> > +       regcache_sync(data->regmap);
> > +       ret = vcnl4035_set_als_power_state(data, VCNL4035_MODE_ALS_ENABLE);
> > +       if (ret < 0)
> > +               return ret;  
> 
> + blank line
> 
> > +       /* wait for 1 ALS integration cycle */
> > +       msleep(data->als_it_val * 100);
> > +
> > +       return 0;
> > +}
> > +#endif  
> 
> > +static const struct of_device_id vcnl4035_of_match[] = {
> > +       { .compatible = "vishay,vcnl4035", },
> > +       { },  
> 
> Better w/o comma.
> 
> > +};
> > +MODULE_DEVICE_TABLE(of, vcnl4035_of_match);  
> 
> > +
> > +static const struct i2c_device_id vcnl4035_id[] = {
> > +       { "vcnl4035", 0 },
> > +       { }
> > +};
> > +MODULE_DEVICE_TABLE(i2c, vcnl4035_id);  
> 
> Are you expecting legacy code to use this? I would rather switch to
> ->probe_new() and also remove this.  
>