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 <20191009200523.8436-3-stuart.w.hayes@gmail.com> <CAHp75Vc1mZ7qxKPGaqDVAQ9d_UjNq9LJDEPWHQHaYCfw7vGrmA@mail.gmail.com>
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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Thu, 10 Oct 2019 08:40:29 +0300
Message-ID: <CAHp75VfNjnAxua6ESx1Vp=57O=pVM10P1UK8bGNQUk7FeY=Dmw@mail.gmail.com>
Subject: Re: [PATCH 2/3] PCI: pciehp: Wait for PDS if in-band presence is disabled
To:     Stuart Hayes <stuart.w.hayes@gmail.com>
Cc:     Bjorn Helgaas <bhelgaas@google.com>,
        Austin Bolen <austin_bolen@dell.com>,
        Keith Busch <keith.busch@intel.com>,
        Alexandru Gagniuc <mr.nuke.me@gmail.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        "Gustavo A . R . Silva" <gustavo@embeddedor.com>,
        Sinan Kaya <okaya@kernel.org>,
        Oza Pawandeep <poza@codeaurora.org>, linux-pci@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Lukas Wunner <lukas@wunner.de>
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On Thu, Oct 10, 2019 at 8:37 AM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Wed, Oct 9, 2019 at 11:05 PM Stuart Hayes <stuart.w.hayes@gmail.com> wrote:

> > +static void pcie_wait_for_presence(struct pci_dev *pdev)
> > +{
> > +       int timeout = 1250;

> > +       bool pds;

Also this is redundant. Just use the following outside the loop

 if (!retries)
   pc_info(...);

.

> > +       u16 slot_status;
> > +
> > +       while (true) {
> > +               pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
> > +               pds = !!(slot_status & PCI_EXP_SLTSTA_PDS);
> > +               if (pds || timeout <= 0)
> > +                       break;
> > +               msleep(10);
> > +               timeout -= 10;
> > +       }
>
> Can we avoid infinite loops? They are hard to parse (in most cases,
> and especially when it's a timeout loop)
>
> unsigned int retries = 125; // 1250 ms
>
> do {
>  ...
> } while (--retries);
>
> > +
> > +       if (!pds)
> > +               pci_info(pdev, "Presence Detect state not set in 1250 msec\n");
> > +}
>
> --
> With Best Regards,
> Andy Shevchenko


-- 
With Best Regards,
Andy Shevchenko