RE: [PATCH v9 tty-next 2/4] serial: 8250_pci1xxxx: Add driver for quad-uart support

[Tharunkumar.Pasumarthi]

> From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Sent: Friday, December 16, 2022 1:56 PM
> To: Tharunkumar Pasumarthi - I67821
> <Tharunkumar.Pasumarthi@xxxxxxxxxxxxx>
> Subject: Re: [PATCH v9 tty-next 2/4] serial: 8250_pci1xxxx: Add driver for
> quad-uart support
> 
> > > > +             pci_iounmap(pdev, priv->membase);
> > >
> > > Here is inconsistency on how you interpret pci_*() calls when
> > > pcim_enable_device() has been used. I.e. for IRQ you don't
> > > deallocate resources explicitly (yes, it's done automatically
> > > anyway), but you explicitly call pci_iounmap(). Choose a single approach
> for all of them.
> >
> > AFAIK call to pci_iounmap cannot be avoided since pci_ioremap_bar is not
> 'managed' API.
> > You suggest calling pci_free_irq_vectors (even though it is not mandatory)?
> 
> Why is it not mandatory?

Hi Andy,

Following is the reason why I felt calling pci_free_irq_vectors is not mandatory.
Correct me if my understanding is wrong.

Following is the Callback Sequence (from 6.1 kernel) that gets executed upon calling pci_alloc_irq_vectors:
pci_alloc_irq_vectors =>
 pci_alloc_irq_vectors_affinity =>
__pci_enable_msi_range =>
 pci_setup_msi_context =>
 pcim_setup_msi_release =>

devm_add_action(&dev->dev, pcim_msi_release, dev);

Inside pcim_msi_release: (called since pcim_enable_device is used)
pci_free_irq_vectors(dev);

>From this sequence, it seemed like, kernel takes care of freeing irq and calling pci_free_irq_vectors is not required. 

Thanks,
Tharun Kumar P