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

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Message-ID: <VI1PR04MB57927A11B589323E30E45BF884630@VI1PR04MB5792.eurprd04.prod.outlook.com>
Date:   Mon, 18 Feb 2019 07:15:22 +0000
From:   "Z.q. Hou" <zhiqiang.hou@....com>
To:     Bjorn Helgaas <helgaas@...nel.org>,
        Subrahmanya Lingappa <l.subrahmanya@...iveil.co.in>
CC:     "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

Hi Bjorn,

Thanks a lot for your comments!

> -----Original Message-----
> From: Bjorn Helgaas <helgaas@...nel.org>
> Sent: 2019年2月8日 22:13
> To: Subrahmanya Lingappa <l.subrahmanya@...iveil.co.in>
> Cc: Z.q. Hou <zhiqiang.hou@....com>; mark.rutland@....com;
> devicetree@...r.kernel.org; lorenzo.pieralisi@....com; Xiaowei Bao
> <xiaowei.bao@....com>; linux-pci@...r.kernel.org; will.deacon@....com;
> linux-kernel@...r.kernel.org; Leo Li <leoyang.li@....com>; M.h. Lian
> <minghuan.lian@....com>; robh+dt@...nel.org; Mingkai Hu
> <mingkai.hu@....com>; catalin.marinas@....com; shawnguo@...nel.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.

Yes, will split this patch in next version.

> 
> 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).

It is not a bug, but the bug is to limit multiple function EP (devfn > 0).

Thanks,
Zhiqiang