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Message-ID: <CAL5oW02uRk-ZLMaE6Skt7rX6xy=sQNttfSZ2N1JRBXPfjJpZNg@mail.gmail.com>
Date: Thu, 10 Oct 2019 15:37:28 -0500
From: Stuart Hayes <stuart.w.hayes@...il.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
Austin Bolen <austin_bolen@...l.com>,
Keith Busch <keith.busch@...el.com>,
Alexandru Gagniuc <mr.nuke.me@...il.com>,
"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
"Gustavo A . R . Silva" <gustavo@...eddedor.com>,
Sinan Kaya <okaya@...nel.org>,
Oza Pawandeep <poza@...eaurora.org>, linux-pci@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Lukas Wunner <lukas@...ner.de>
Subject: Re: [PATCH 2/3] PCI: pciehp: Wait for PDS if in-band presence is disabled
On Thu, Oct 10, 2019 at 12:40 AM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>
> On Thu, Oct 10, 2019 at 8:37 AM Andy Shevchenko
> <andy.shevchenko@...il.com> wrote:
> > On Wed, Oct 9, 2019 at 11:05 PM Stuart Hayes <stuart.w.hayes@...il.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
Thank you for the feedback! An infinite loop is used several other places in
this driver--this keeps the style similar. I can change it as you suggest,
though, if that would be preferable to consistency.
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