On Wed, Oct 9, 2019 at 11:05 PM Stuart Hayes <stuart.w.hayes@xxxxxxxxx> wrote:
>
> From: Alexandru Gagniuc <mr.nuke.me@xxxxxxxxx>
>
> When inband presence is disabled, PDS may come up at any time, or not
> at all. PDS being low may indicate that the card is still mating, and
> we could expect contact bounce to bring down the link as well.
>
> It is reasonable to assume that most cards will mate in a hotplug slot
> in about a second. Thus, when we know PDS only reflects out-of-band
> presence, it's worthwhile to wait the extra second or so to make sure
> the card is properly mated before loading the driver, and to prevent
> the hotplug code from disabling a device if the presence detect change
> goes active after the device is enabled.
> +static void pcie_wait_for_presence(struct pci_dev *pdev)
> +{
> + int timeout = 1250;
> + bool pds;
> + 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
