linux-kernel - Re: [PATCH v13 5/6] PCI: Unify wait for link active into generic PCI

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Date:   Mon, 9 Apr 2018 17:25:28 -0600
From:   Keith Busch <keith.busch@...el.com>
To:     Oza Pawandeep <poza@...eaurora.org>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dongdong Liu <liudongdong3@...wei.com>,
        Wei Zhang <wzhang@...com>, Sinan Kaya <okaya@...eaurora.org>,
        Timur Tabi <timur@...eaurora.org>
Subject: Re: [PATCH v13 5/6] PCI: Unify wait for link active into generic PCI

On Mon, Apr 09, 2018 at 10:41:53AM -0400, Oza Pawandeep wrote:
> +/**
> + * pcie_wait_for_link - Wait for link till it's active/inactive
> + * @pdev: Bridge device
> + * @active: waiting for active or inactive ?
> + *
> + * Use this to wait till link becomes active or inactive.
> + */
> +bool pcie_wait_for_link(struct pci_dev *pdev, bool active)
> +{
> +	int timeout = 1000;
> +	bool ret;
> +	u16 lnk_status;
> +
> +	for (;;) {
> +		pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
> +		ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
> +		if (ret == active)
> +			return true;
> +		if (timeout <= 0)
> +			break;
> +		timeout -= 10;
> +	}

This is missing an msleep(10) at each iteration.

> +
> +	pci_info(pdev, "Data Link Layer Link Active not %s in 1000 msec\n",
> +		 active ? "set" : "cleared");
> +
> +	return false;
> +}