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Message-ID: <Y5w8o0vK7wuoX+yh@smile.fi.intel.com>
Date: Fri, 16 Dec 2022 11:38:43 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Tharunkumar.Pasumarthi@...rochip.com
Cc: Kumaravel.Thiagarajan@...rochip.com, linux-kernel@...r.kernel.org,
linux-serial@...r.kernel.org, gregkh@...uxfoundation.org,
jirislaby@...nel.org, ilpo.jarvinen@...ux.intel.com,
macro@...am.me.uk, cang1@...e.co.uk, colin.i.king@...il.com,
phil.edworthy@...esas.com, biju.das.jz@...renesas.com,
geert+renesas@...der.be, lukas@...ner.de,
u.kleine-koenig@...gutronix.de, wander@...hat.com,
etremblay@...tech-controls.com, jk@...abs.org,
UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH v9 tty-next 2/4] serial: 8250_pci1xxxx: Add driver for
quad-uart support
On Fri, Dec 16, 2022 at 09:30:42AM +0000, Tharunkumar.Pasumarthi@...rochip.com wrote:
> > From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > Sent: Friday, December 16, 2022 1:56 PM
...
> > > > > + 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?
>
> 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.
Technically you are correct, but... read this discussion, and pay attention to
what Christoph said there:
https://lore.kernel.org/linux-serial/0250c46e-da6c-71f3-50ae-b7c17fd0bd2c@siemens.com/
--
With Best Regards,
Andy Shevchenko
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