linux-kernel - Re: [PATCHv3 17/27] PCI: mobiveil: fix the checking of valid device

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Message-ID: <20190208141315.GU7268@google.com>
Date:   Fri, 8 Feb 2019 08:13:15 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Subrahmanya Lingappa <l.subrahmanya@...iveil.co.in>
Cc:     "Z.q. Hou" <zhiqiang.hou@....com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        Xiaowei Bao <xiaowei.bao@....com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "will.deacon@....com" <will.deacon@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Leo Li <leoyang.li@....com>,
        "M.h. Lian" <minghuan.lian@....com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        Mingkai Hu <mingkai.hu@....com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCHv3 17/27] PCI: mobiveil: fix the checking of valid device

[+cc Thomas]

On Fri, Feb 08, 2019 at 06:11:15PM +0530, Subrahmanya Lingappa wrote:
> On Tue, Jan 29, 2019 at 1:40 PM Z.q. Hou <zhiqiang.hou@....com> wrote:
> >
> > From: Hou Zhiqiang <Zhiqiang.Hou@....com>
> >
> > Avoid to issue CFG transactions to link partner when the PCIe
> > link is not up. And allow CFG transactions to all functions of
> > Endpoint implemented multiple functions.
> >
> > Fixes: 9af6bcb11e12 ("PCI: mobiveil: Add Mobiveil PCIe Host
> > Bridge IP driver")
> > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@....com>
> > Reviewed-by: Minghuan Lian <Minghuan.Lian@....com>
> > ---
> > V3:
> >  - No change
> >
> >  drivers/pci/controller/mobiveil/pcie-mobiveil-host.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/controller/mobiveil/pcie-mobiveil-host.c b/drivers/pci/controller/mobiveil/pcie-mobiveil-host.c
> > index dc5324d94466..1ae82e790562 100644
> > --- a/drivers/pci/controller/mobiveil/pcie-mobiveil-host.c
> > +++ b/drivers/pci/controller/mobiveil/pcie-mobiveil-host.c
> > @@ -29,6 +29,10 @@ static bool mobiveil_pcie_valid_device(struct pci_bus *bus, unsigned int devfn)
> >  {
> >         struct mobiveil_pcie *pcie = bus->sysdata;
> >
> > +       /* If there is no link, then there is no device */
> > +       if (bus->number > pcie->rp.root_bus_nr && !mobiveil_pcie_link_up(pcie))
> > +               return false;
> > +
> >         /* Only one device down on each root port */
> >         if ((bus->number == pcie->rp.root_bus_nr) && (devfn > 0))
> >                 return false;
> > @@ -37,7 +41,7 @@ static bool mobiveil_pcie_valid_device(struct pci_bus *bus, unsigned int devfn)
> >          * Do not read more than one device on the bus directly
> >          * attached to RC
> >          */
> > -       if ((bus->primary == pcie->rp.root_bus_nr) && (devfn > 0))
> > +       if ((bus->primary == pcie->rp.root_bus_nr) && (PCI_SLOT(devfn) > 0))

> here change "primary" to "number", as it's a bug in the original driver too.

This looks like it should be split into two patches: (1) checking for
link up, and (2) checking root_bus_nr.

And if you mean "bus->primary == pcie->rp.root_bus_nr" is a bug in
pci-aardvark.c, too, it is imperative to fix that bug also (with a
separate patch).

> >                 return false;
> >
> >         return true;
> > --
> > 2.17.1
> >
> 
> _______________________________________________
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> linux-arm-kernel@...ts.infradead.org
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