linux-kernel - Re: [PATCH v2 3/3] PCI: iproc: Display PCIe Link information

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Message-ID: <CABe79T72=Hd7NBh664_fOudpxB5z+iiBKTBQC3=XqJRy9Oqs+A@mail.gmail.com>
Date:   Thu, 17 Sep 2020 08:42:56 +0530
From:   Srinath Mannam <srinath.mannam@...adcom.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Ray Jui <rjui@...adcom.com>, linux-pci@...r.kernel.org,
        BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 3/3] PCI: iproc: Display PCIe Link information

On Thu, Sep 17, 2020 at 7:22 AM Rob Herring <robh@...nel.org> wrote:
>
Hi Rob,
Thanks for review.
> On Tue, Sep 15, 2020 at 07:15:41PM +0530, Srinath Mannam wrote:
> > After successful linkup more comprehensive information about PCIe link
> > speed and link width will be displayed to the console.
> >
> > Signed-off-by: Srinath Mannam <srinath.mannam@...adcom.com>
> > ---
> >  drivers/pci/controller/pcie-iproc.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/pci/controller/pcie-iproc.c b/drivers/pci/controller/pcie-iproc.c
> > index cc5b7823edeb..8ef2d1fe392c 100644
> > --- a/drivers/pci/controller/pcie-iproc.c
> > +++ b/drivers/pci/controller/pcie-iproc.c
> > @@ -1479,6 +1479,7 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res)
> >  {
> >       struct device *dev;
> >       int ret;
> > +     struct pci_dev *pdev;
> >       struct pci_host_bridge *host = pci_host_bridge_from_priv(pcie);
> >
> >       dev = pcie->dev;
> > @@ -1542,6 +1543,11 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res)
> >               goto err_power_off_phy;
> >       }
> >
> > +     for_each_pci_bridge(pdev, host->bus) {
> > +             if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT)
> > +                     pcie_print_link_status(pdev);
> > +     }
>
> If this information is useful for 1 host implementation, why not all of
> them and put this in a common spot.
In common, pcie_print_link_status() is called during pci device caps
initialization, if the available link bandwidth is less than capabilities
of devices. Few EP drivers also used this function to print link
bandwidth info. This host can be configured for different link
speeds and link widths on different platforms so we thought
displaying link bandwidth after successful linkup is helpful to
know link details.

Thanks & Regards,
Srinath.
>
> Rob