linux-kernel - Re: [PATCH 3/4] MIPS: PCI: Return PCIBIOS_* from tx4927_pci_config

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Date: Tue, 6 Feb 2024 16:25:06 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Sergio Paracuellos <sergio.paracuellos@...il.com>
cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>, 
    linux-mips@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/4] MIPS: PCI: Return PCIBIOS_* from
 tx4927_pci_config_read/write()

On Mon, 5 Feb 2024, Sergio Paracuellos wrote:
> On Mon, Feb 5, 2024 at 3:35 PM Ilpo Järvinen
> <ilpo.jarvinen@...ux.intel.com> wrote:
> >
> > pci_ops .read/.write must return PCIBIOS_* codes but
> > tx4927_pci_config_read/write() return -1 when mkaddr() cannot find
> > devfn from the root bus. Return PCIBIOS_DEVICE_NOT_FOUND instead and
> > pass that onward in the call chain instead of overwriting the return
> > value.
> >
> > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> > ---
> >  arch/mips/pci/ops-tx4927.c | 14 +++++++++-----
> >  1 file changed, 9 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/mips/pci/ops-tx4927.c b/arch/mips/pci/ops-tx4927.c
> > index f7802f100401..4dd8b93985fb 100644
> > --- a/arch/mips/pci/ops-tx4927.c
> > +++ b/arch/mips/pci/ops-tx4927.c
> > @@ -60,7 +60,7 @@ static int mkaddr(struct pci_bus *bus, unsigned int devfn, int where,
> >  {
> >         if (bus->parent == NULL &&
> >             devfn >= PCI_DEVFN(TX4927_PCIC_MAX_DEVNU, 0))
> > -               return -1;
> > +               return PCIBIOS_DEVICE_NOT_FOUND;
> >         __raw_writel(((bus->number & 0xff) << 0x10)
> >                      | ((devfn & 0xff) << 0x08) | (where & 0xfc)
> >                      | (bus->parent ? 1 : 0),
> 
> Should we also return PCIBIOS_SUCCESSFUL instead of 'return 0' in
> 'mkaddr' for coherency?

Yeah right, I'll change it too.

I didn't take notice of that because the reason for all this is that I 
intend to convert these functions to return generic errno and push the 
PCIBIOS error code -> errno conversion into where it's really needed (real 
PCIBIOS access functions in arch/x86/pci/pcbios.c). Returning 0 as literal 
is very common cosmetic "error" in these functions. While calculating the 
error rate in return values of these functions (I'm able to do that 
because of the audit), those were not even included to 15% returning 
-Esomething instead of PCIBIOS_*. It would be way above that if I'd count 
return 0 also as an error.

> Other than that, changes look good to me.
> 
> Reviewed-by: Sergio Paracuellos <sergio.paracuellos@...il.com>

Thanks for the review.

-- 
 i.