On Tue, Mar 6, 2012 at 12:13 AM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> Current code will create rescan for every pci device under parent bus.
> that is not right. the device is already there, there is no reason to rescan it.
>
> We could have rescan for pci bridges. less confusing.
Yes, but now we have *three* rescan attributes for a single bridge/bus:
/sys/devices/pci0000:00/0000:00:01.0/pci_bus/0000:01/rescan
/sys/devices/pci0000:00/0000:00:01.0/rescan_bridge
/sys/devices/pci0000:00/0000:00:01.0/rescan
and this for an endpoint:
/sys/devices/pci0000:00/0000:00:05.0/rescan
I think endpoints should not have a "rescan" attribute at all, and
bridges should have only a "rescan" attribute (not "rescan" and
"rescan_bridge").
I'm not sure about "pci_bus/.../rescan". I know you didn't add that,
but I'm not sure it makes sense to have both that and a "rescan" on
the bridge device. If we have both, what's the difference between
them?
> Need to move rescan attr to pci dev bridge attribute group.
> And We should rescan bridge's secondary bus instead of primary bus.
>
> -v3: Use device_type for pci dev.
> -v4: Seperate pci device type change out
> -v5: add rescan_bridge for bridge type, and still keep the old rescan.
> may remove the old rescan later.
>
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
> Documentation/ABI/testing/sysfs-bus-pci | 10 ++++++++++
> drivers/pci/pci-sysfs.c | 24 ++++++++++++++++++++++++
> 2 files changed, 34 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
> index 34f5110..95f0f37 100644
> --- a/Documentation/ABI/testing/sysfs-bus-pci
> +++ b/Documentation/ABI/testing/sysfs-bus-pci
> @@ -111,6 +111,16 @@ Description:
> from this part of the device tree.
> Depends on CONFIG_HOTPLUG.
>
> +What: /sys/bus/pci/devices/.../rescan_bridge
> +Date: February 2012
> +Contact: Linux PCI developers <linux-pci@xxxxxxxxxxxxxxx>
> +Description:
> + Writing a non-zero value to this attribute will
> + force a rescan of the bridge and all child buses, and
> + re-discover devices removed earlier from this part of
> + the device tree.
> + Depends on CONFIG_HOTPLUG.
> +
> What: /sys/bus/pci/devices/.../reset
> Date: July 2009
> Contact: Michael S. Tsirkin <mst@xxxxxxxxxx>
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index 39d15e6..d5c8ffb 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -325,6 +325,27 @@ dev_rescan_store(struct device *dev, struct device_attribute *attr,
> return count;
> }
>
> +static ssize_t
> +dev_bridge_rescan_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + unsigned long val;
> + struct pci_dev *pdev = to_pci_dev(dev);
> +
> + if (kstrtoul(buf, 0, &val) < 0)
> + return -EINVAL;
> +
> + if (val) {
> + mutex_lock(&pci_remove_rescan_mutex);
> + pci_rescan_bus(pdev->subordinate);
> + mutex_unlock(&pci_remove_rescan_mutex);
> + }
> + return count;
> +}
> +
> +static struct device_attribute pci_dev_bridge_rescan_attr =
> + __ATTR(rescan_bridge, (S_IWUSR|S_IWGRP), NULL, dev_bridge_rescan_store);
> +
> static void remove_callback(struct device *dev)
> {
> struct pci_dev *pdev = to_pci_dev(dev);
> @@ -1337,6 +1358,9 @@ static int __init pci_sysfs_init(void)
> late_initcall(pci_sysfs_init);
>
> static struct attribute *pci_dev_bridge_attrs[] = {
> +#ifdef CONFIG_HOTPLUG
> + &pci_dev_bridge_rescan_attr.attr,
> +#endif
> NULL,
> };
>
> --
> 1.7.7
>
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