linux-kernel - Re: [PATCH v2 7/8] PCI: xgene: Do PCI error check on own line

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Date:   Tue, 29 Aug 2023 19:23:52 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Rob Herring <robh@...nel.org>
cc:     linux-pci@...r.kernel.org, Bjorn Helgaas <helgaas@...nel.org>,
        Andi Shyti <andi.shyti@...nel.org>,
        Philippe Mathieu-Daudé <philmd@...aro.org>,
        Toan Le <toan@...amperecomputing.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-arm-kernel@...ts.infradead.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 7/8] PCI: xgene: Do PCI error check on own line

On Tue, 29 Aug 2023, Ilpo Järvinen wrote:

> On Tue, 29 Aug 2023, Rob Herring wrote:
> 
> > On Sun, Aug 27, 2023 at 8:37 AM Ilpo Järvinen
> > <ilpo.jarvinen@...ux.intel.com> wrote:
> > >
> > > Instead of a if condition with a line split, use the usual error
> > > handling pattern with a separate variable to improve readability.
> > >
> > > No functional changes intended.
> > >
> > > Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> > > ---
> > >  drivers/pci/controller/pci-xgene.c | 5 +++--
> > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/pci/controller/pci-xgene.c b/drivers/pci/controller/pci-xgene.c
> > > index 887b4941ff32..b7f338de160b 100644
> > > --- a/drivers/pci/controller/pci-xgene.c
> > > +++ b/drivers/pci/controller/pci-xgene.c
> > > @@ -163,9 +163,10 @@ static int xgene_pcie_config_read32(struct pci_bus *bus, unsigned int devfn,
> > >                                     int where, int size, u32 *val)
> > >  {
> > >         struct xgene_pcie *port = pcie_bus_to_port(bus);
> > > +       int ret;
> > >
> > > -       if (pci_generic_config_read32(bus, devfn, where & ~0x3, 4, val) !=
> > > -           PCIBIOS_SUCCESSFUL)
> > > +       ret = pci_generic_config_read32(bus, devfn, where & ~0x3, 4, val);
> > > +       if (ret != PCIBIOS_SUCCESSFUL)
> > 
> > Long term I think we want to replace these error codes with standard
> > linux ones.
> 
> This series is preparatory work for this very goal you stated!
> 
> > As PCIBIOS_SUCCESSFUL is 0, I would change this to just:
> > 
> > if (pci_generic_config_read32(bus, devfn, where & ~0x3, 4, val))
> >     return PCIBIOS_DEVICE_NOT_FOUND;
> 
> I'm not so sure about this suggestion as it will overwrite the original 
> error code (like the current approach unfortunately also does). To me it 
> would seem more appropriate is to return the original error code instead. 
> But more discussion is needed before making such changes to values these 
> functions return. (And there are plenty of similar examples besides this 
> one.)

Actually, it looks in this case I could do that transformation safely now
since pci_generic_config_read32() can only return either 
PCIBIOS_DEVICE_NOT_FOUND or PCIBIOS_SUCCESSFUL so it won't alter anything.

-- 
 i.