linux-kernel - Re: [PATCH -v2 3/3] PCI,pciehp: use PCIe DSN to identify device change during suspend

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Date:	Thu, 11 Jul 2013 06:04:09 -0400
From:	Don Dutile <ddutile@...hat.com>
To:	Yijing Wang <wangyijing@...wei.com>
CC:	Bjorn Helgaas <bhelgaas@...gle.com>, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, Rafael <rjw@...k.pl>,
	Hanjun Guo <guohanjun@...wei.com>, jiang.liu@...wei.com,
	Paul Bolle <pebolle@...cali.nl>,
	Oliver Neukum <oneukum@...e.de>,
	Gu Zheng <guz.fnst@...fujitsu.com>
Subject: Re: [PATCH -v2 3/3] PCI,pciehp: use PCIe DSN to identify device change
 during suspend

Sorry, did a 'reply' instead of 'reply all' on first reply to this patch...
excuse any repeat...
- Don

On 07/11/2013 05:43 AM, Yijing Wang wrote:
> If device was removed from slot and reinsert a new device during
> suspend, pciehp can not identify the physical device change now.
> So the old driver .resume() method will be called for the new device,
> this is bad. If device support device serial number capability,
> we can identify this by DSN. So the reasonable way is first remove
> the old device, then enable the new device.
>
> Signed-off-by: Yijing Wang<wangyijing@...wei.com>
> Cc: Paul Bolle<pebolle@...cali.nl>
> Cc: "Rafael J. Wysocki"<rjw@...k.pl>
> Cc: Oliver Neukum<oneukum@...e.de>
> Cc: Gu Zheng<guz.fnst@...fujitsu.com>
> Cc: linux-pci@...r.kernel.org
> ---
>   drivers/pci/hotplug/pciehp_core.c |   45 +++++++++++++++++++++++++++++++++++++
>   1 files changed, 45 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
> index 1542735..f2eb214 100644
> --- a/drivers/pci/hotplug/pciehp_core.c
> +++ b/drivers/pci/hotplug/pciehp_core.c
> @@ -296,11 +296,38 @@ static int pciehp_suspend (struct pcie_device *dev)
>   	return 0;
>   }
>
> +/*
> + * check the func 0 device serial number is changed,
> + * if device does not support device serial number,
> + * return false.
> + */
> +static bool device_serial_number_changed(struct pci_bus *pbus)
> +{
> +	u64 old_dsn, new_dsn;
> +	struct pci_dev *pdev;
> +
> +	pdev = pci_get_slot(pbus, PCI_DEVFN(0, 0));
> +	if (!pdev)
> +		return false;
> +
> +	old_dsn = pdev->sn;
> +
> +	/* get func 0 device serial number */
> +	new_dsn = pci_device_serial_number(pdev);
Due to previous recommended change to 1/3 patch, above would be:
     pci_device_serial_number(pdev);

> +	pci_dev_put(pdev);
> +
> +	if (old_dsn != new_dsn)
> +		return true;
> +
and above would be:
     new_dsn = pdev->dsn;
     pci_dev_put(pdev);
     if(pdev->dsn != old_dsn)
         return true;

> +	return false;
> +}
> +
>   static int pciehp_resume (struct pcie_device *dev)
>   {
>   	struct controller *ctrl;
>   	struct slot *slot;
>   	struct pci_bus *pbus = dev->port->subordinate;
> +	int retval = 0;
>   	u8 status;
>
>   	ctrl = get_service_data(dev);
> @@ -315,6 +342,24 @@ static int pciehp_resume (struct pcie_device *dev)
>   	if (status) {
>   		if (list_empty(&pbus->devices))
>   			pciehp_enable_slot(slot);
> +
> +		if (device_serial_number_changed(pbus)) {
> +			/*
> +			 * first power off slot, avoid the old driver
> +			 * .remove() method touch the new hardware
> +			 */
> +			if (POWER_CTRL(ctrl)) {
> +				retval = pciehp_power_off_slot(slot);
> +				if (retval) {
> +					ctrl_err(ctrl,
> +						"Issue of Slot Disable command failed\n");
> +					return 0;
> +				}
> +				msleep(1000);
> +				pciehp_unconfigure_device(slot);
> +				pciehp_enable_slot(slot);
> +			}
> +		}
>   	} else if (!list_empty(&pbus->devices))
>   		pciehp_disable_slot(slot);
>   	

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