On Fri, Jul 12, 2013 at 3:32 AM, Yijing Wang <wangyijing@xxxxxxxxxx> 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@xxxxxxxxxx>
> Cc: Paul Bolle <pebolle@xxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
> Cc: Oliver Neukum <oneukum@xxxxxxx>
> Cc: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx>
> Cc: linux-pci@xxxxxxxxxxxxxxx
> ---
> 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 7fe9dbd..bc47f8e 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);
> + pci_dev_put(pdev);
> +
> + if (old_dsn != new_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);
> + }
> + }
I'm not sure this is implemented at the correct place. The idea of
using the serial number to detect card swaps is not really specific to
pciehp. I know the Device Serial Number capability is defined in the
PCIe spec, but it doesn't *require* any PCIe functionality, and
there's no reason a similar capability couldn't be defined for
conventional PCI.
I don't know much about it, but conventional PCI *does* in fact
support the VPD capability, which can contain a serial number. I
wonder if we should enhance pci_device_serial_number() to look for a
VPD serial number if there's no PCIe DSN. Then we would want this
check for card swap in a more generic place, e.g., somewhere in
pci_scan_slot(), so all forms of hotplug would benefit from it.
Also, I think it's possible to use acpiphp for ExpressCard slots, and
this patch doesn't help acpiphp detect card swaps. I don't see any
mention of suspend/resume in acpiphp, so I don't know if it does
anything at all to detect card changes while suspended. Maybe Rafael
can shed some light?
I put the first two patches on a pci/yijing-dsn-v3 branch while we
work out the details of this one.
Bjorn
> } else if (!list_empty(&pbus->devices)) {
> pciehp_disable_slot(slot);
> }
> --
> 1.7.1
>
>
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