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Subject: Re: [PATCH v6 2/4] iio: adc: Add Xilinx AMS driver

...

> >
> > > + if (IS_ERR(ams->base))
> > > + return PTR_ERR(ams->base);
> > > +
> > > + ams->clk = devm_clk_get(&pdev->dev, NULL);
> > > + if (IS_ERR(ams->clk))
> > > + return PTR_ERR(ams->clk);
> > > + clk_prepare_enable(ams->clk);
> > > + devm_add_action_or_reset(&pdev->dev, (void
> > *)clk_disable_unprepare,
> > > + ams->clk);
> > > +
> > > + INIT_DELAYED_WORK(&ams->ams_unmask_work,
> > ams_unmask_worker);
> > > + devm_add_action_or_reset(&pdev->dev, (void
> > *)cancel_delayed_work,
> >
> > I'm not keen on casting away the function pointer type. Normally we'd just
> > wrap it in a local function, to make it clear it was deliberate and avoid
> > potential nasty problems if the signature of the function ever changes.
> >
> > It's 3 lines of boilerplate, but will give me warm fuzzy feelings!
> > Same for the other case above. The fact this isn't done in exising kernel code
> > make this particularly risky.
>
> Makes sense. I will revert the code back to its original and handle the cases using goto
> and inside remove()
Ah. Not what I meant. I was suggesting you add a little function locally
that has the right type and in turn calls cancel_delayed_work().

As that directly exposes the actual function calls, any signature change in future
will cause compile breakage (or be picked up any automated tools doing that refactor).

>
> >
> > > + &ams->ams_unmask_work);
> > > +
> > > + ret = ams_init_device(ams);
> > > + if (ret) {
> > > + dev_err(&pdev->dev, "failed to initialize AMS\n");
> > > + return ret;
> > > + }
> > > +
> > > + ret = ams_parse_dt(indio_dev, pdev);
> > > + if (ret) {
> > > + dev_err(&pdev->dev, "failure in parsing DT\n");
> > > + return ret;
> > > + }
> > > +
> > > + ams_enable_channel_sequence(indio_dev);
> > > +
> > > + ams->irq = platform_get_irq(pdev, 0);
> >
> > platform_get_irq () can return errors, in particular -EPROBE_DEFER so I'd
> > check that and return before you call devm_request_irq() I'm not sure
> > devm_request_irq() will not eat that error code.
> >
>
> Will fix this in next series.
>
> >
> > > + ret = devm_request_irq(&pdev->dev, ams->irq, &ams_irq, 0, "ams-
> > irq",
> > > + indio_dev);
> > > + if (ret < 0) {
> > > + dev_err(&pdev->dev, "failed to register interrupt\n");
> > > + return ret;
> > > + }
> > > +
> > > + platform_set_drvdata(pdev, indio_dev);
> > > +
> > > + return iio_device_register(indio_dev); }
> > > +
> > > +static int ams_remove(struct platform_device *pdev) {
> > > + struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> > > +
> > > + iio_device_unregister(indio_dev);
> >
> > If this is all you have in remove, then you can use devm_iio_device_register()
> > in probe() and not need an remove() callback at all.
>
> I think remove will have more functions since I am getting rid of devm_add_action_or_reset()

See above.

J

>
> >
> > > +
> > > + return 0;
> > > +}
> > > +
> >
> > ...

2021-07-19 07:53:21

by Anand Ashok Dumbre

[permalink] [raw]

Subject: RE: [PATCH v6 2/4] iio: adc: Add Xilinx AMS driver

> -----Original Message-----
> From: Jonathan Cameron <[email protected]>
> Sent: Thursday 15 July 2021 1:52 PM
> To: Anand Ashok Dumbre <[email protected]>
> Cc: Jonathan Cameron <[email protected]>; [email protected]; linux-
> [email protected]; git-dev <[email protected]>; Michal Simek
> <[email protected]>; [email protected]; [email protected];
> [email protected]; Manish Narani <[email protected]>
> Subject: Re: [PATCH v6 2/4] iio: adc: Add Xilinx AMS driver
>
> ...
>
> > >
> > > > + if (IS_ERR(ams->base))
> > > > + return PTR_ERR(ams->base);
> > > > +
> > > > + ams->clk = devm_clk_get(&pdev->dev, NULL);
> > > > + if (IS_ERR(ams->clk))
> > > > + return PTR_ERR(ams->clk);
> > > > + clk_prepare_enable(ams->clk);
> > > > + devm_add_action_or_reset(&pdev->dev, (void
> > > *)clk_disable_unprepare,
> > > > + ams->clk);
> > > > +
> > > > + INIT_DELAYED_WORK(&ams->ams_unmask_work,
> > > ams_unmask_worker);
> > > > + devm_add_action_or_reset(&pdev->dev, (void
> > > *)cancel_delayed_work,
> > >
> > > I'm not keen on casting away the function pointer type. Normally
> > > we'd just wrap it in a local function, to make it clear it was
> > > deliberate and avoid potential nasty problems if the signature of the
> function ever changes.
> > >
> > > It's 3 lines of boilerplate, but will give me warm fuzzy feelings!
> > > Same for the other case above. The fact this isn't done in exising
> > > kernel code make this particularly risky.
> >
> > Makes sense. I will revert the code back to its original and handle
> > the cases using goto and inside remove()
> Ah. Not what I meant. I was suggesting you add a little function locally that
> has the right type and in turn calls cancel_delayed_work().
>
> As that directly exposes the actual function calls, any signature change in
> future will cause compile breakage (or be picked up any automated tools
> doing that refactor).

Now I understand.
Will fix it in the next series.

>
> >
> > >
> > > > + &ams->ams_unmask_work);
> > > > +
> > > > + ret = ams_init_device(ams);
> > > > + if (ret) {
> > > > + dev_err(&pdev->dev, "failed to initialize AMS\n");
> > > > + return ret;
> > > > + }
> > > > +
> > > > + ret = ams_parse_dt(indio_dev, pdev);
> > > > + if (ret) {
> > > > + dev_err(&pdev->dev, "failure in parsing DT\n");
> > > > + return ret;
> > > > + }
> > > > +
> > > > + ams_enable_channel_sequence(indio_dev);
> > > > +
> > > > + ams->irq = platform_get_irq(pdev, 0);
> > >
> > > platform_get_irq () can return errors, in particular -EPROBE_DEFER
> > > so I'd check that and return before you call devm_request_irq() I'm
> > > not sure
> > > devm_request_irq() will not eat that error code.
> > >
> >
> > Will fix this in next series.
> >
> > >
> > > > + ret = devm_request_irq(&pdev->dev, ams->irq, &ams_irq, 0, "ams-
> > > irq",
> > > > + indio_dev);
> > > > + if (ret < 0) {
> > > > + dev_err(&pdev->dev, "failed to register interrupt\n");
> > > > + return ret;
> > > > + }
> > > > +
> > > > + platform_set_drvdata(pdev, indio_dev);
> > > > +
> > > > + return iio_device_register(indio_dev); }
> > > > +
> > > > +static int ams_remove(struct platform_device *pdev) {
> > > > + struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> > > > +
> > > > + iio_device_unregister(indio_dev);
> > >
> > > If this is all you have in remove, then you can use
> > > devm_iio_device_register() in probe() and not need an remove() callback
> at all.
> >
> > I think remove will have more functions since I am getting rid of
> > devm_add_action_or_reset()
>
> See above.
>
> J
>
> >
> > >
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > >
> > > ...

Thanks,
Anand