Re: [PATCH 7/9] ethernet: stmicro: Simplify PCI devres usage

Andy Shevchenko
2024-08-20T10:37:42Z

On Tue, Aug 20, 2024 at 09:52:40AM +0200, Philipp Stanner wrote:
> On Mon, 2024-08-19 at 21:28 +0300, Andy Shevchenko wrote:
> > On Mon, Aug 19, 2024 at 06:51:47PM +0200, Philipp Stanner wrote:

...

> > loongson_dwmac_probe()
> >
> > > + memset(&res, 0, sizeof(res));
> > > + res.addr = pcim_iomap_region(pdev, 0, pci_name(pdev));
> > > + if (IS_ERR(res.addr)) {
> > > + ret = PTR_ERR(res.addr);
> > > + goto err_disable_device;
> >
> > It seems your series reveals issues in the error paths of .probe():s
> > in many drivers...
> >
> > If we use pcim variant to enable device, why do we need to explicitly
> > disable it?
>
> No.

Can you elaborate? No issues being revealed, or no need to disable it
explicitly, or...?

> > >   }

...

> > loongson_dwmac_remove()
> >
> > >   pci_disable_msi(pdev);
> > >   pci_disable_device(pdev);
> >
> > Not sure why we need these either...
>
> It's complicated.
>
> The code uses pciM_enable_device(), but here in remove
> pci_disable_device().
>
> pcim_enable_device() sets up a disable callback which only calls
> pci_disable_device() if pcim_pin_device() has not been called.
>
> This code doesn't seem to call pcim_pin_device(), so I think
> pci_disable_device() could be removed.
>
>
> I definitely would not feel confident touching pci_disable_msi(),
> though. The AFAIK biggest problem remaining in PCI devres is that the
> MSI code base implicitly calls into devres, see here [1]

But isn't it a busyness of PCI core to call pci_disable_msi() at the right
moment? Okay, I admit that there might be devices that require a special
workflow WRT MSI, is this the case here?

> [1] https://lore.kernel.org/all/ee44ea7ac760e73edad3f20b30b4d2fff66c1a85.camel@redhat.com/

--
With Best Regards,
Andy Shevchenko