linux-kernel - Re: [PATCH v3 3/4] i2c: designware: Use the correct name of device-managed function

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Date:   Tue, 16 Feb 2021 18:46:01 +0100
From:   Krzysztof Wilczyński <kw@...ux.com>
To:     Dejin Zheng <zhengdejin5@...il.com>
Cc:     corbet@....net, jarkko.nikula@...ux.intel.com,
        andriy.shevchenko@...ux.intel.com, mika.westerberg@...ux.intel.com,
        rric@...nel.org, helgaas@...nel.org, wsa@...nel.org,
        linux-doc@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/4] i2c: designware: Use the correct name of
 device-managed function

Hi Dejin,

Thank you for all the changes, looks good!

You could improve the subject line, as it is very vague - what is the
new function name more correct?  Was the other and/or the previous one
not correct?  Seems like you are correcting a typo of sorts, rather than
introducing a new function in this file.

> Use the new function pcim_alloc_irq_vectors() to allocate IRQ vectors,
> the pcim_alloc_irq_vectors() function, an explicit device-managed
> version of pci_alloc_irq_vectors(). If pcim_enable_device() has been
> called before, then pci_alloc_irq_vectors() is actually
> a device-managed function. It is used here as a device-managed
> function, So replace it with pcim_alloc_irq_vectors().

The commit is good, but it could use some polish, so to speak.

A few suggestions to think about:

  - What are we adding and/or changing, and why
  - Why is using pcim_alloc_irq_vectors(), which is part
    of the managed devices framework, a better alternative
    to the pci_alloc_irq_vectors()
  - And finally why this change allowed us to remove the
    pci_free_irq_vectors()

> At the same time, simplify the error handling path.

The change simplifies the error handling path, how?  A line of two which
explains how it has been achieved might help should someone reads the
commit message in the future.

[...]
>  	if (controller->setup) {
>  		r = controller->setup(pdev, controller);
> -		if (r) {
> -			pci_free_irq_vectors(pdev);
> +		if (r)
>  			return r;
> -		}
>  	}
>  
>  	i2c_dw_adjust_bus_speed(dev);
> @@ -246,10 +244,8 @@ static int i2c_dw_pci_probe(struct pci_dev *pdev,
>  		i2c_dw_acpi_configure(&pdev->dev);
>  
>  	r = i2c_dw_validate_speed(dev);
> -	if (r) {
> -		pci_free_irq_vectors(pdev);
> +	if (r)
>  		return r;
> -	}
>  
>  	i2c_dw_configure(dev);
>  
> @@ -269,10 +265,8 @@ static int i2c_dw_pci_probe(struct pci_dev *pdev,
>  	adap->nr = controller->bus_num;
>  
>  	r = i2c_dw_probe(dev);
> -	if (r) {
> -		pci_free_irq_vectors(pdev);
> +	if (r)
>  		return r;
> -	}
>  
>  	pm_runtime_set_autosuspend_delay(&pdev->dev, 1000);
>  	pm_runtime_use_autosuspend(&pdev->dev);
> @@ -292,7 +286,6 @@ static void i2c_dw_pci_remove(struct pci_dev *pdev)
>  
>  	i2c_del_adapter(&dev->adapter);
>  	devm_free_irq(&pdev->dev, dev->irq, dev);
> -	pci_free_irq_vectors(pdev);

If pcim_release() is called should the pci_driver's probe callback fail,
and I assume that this is precisely the case, then all of the above make
sense in the view of using pcim_alloc_irq_vectors().

Reviewed-by: Krzysztof Wilczyński <kw@...ux.com>

Krzysztof