Re: [PATCH] Add option to passively listen for PCIE hotplug events

Kenji Kaneshige
2008-11-04T05:47:58Z

Matthew Garrett wrote:
> On Tue, Nov 04, 2008 at 02:07:00AM +0000, Matthew Garrett wrote:
>> On Tue, Nov 04, 2008 at 10:58:11AM +0900, Kenji Kaneshige wrote:
>>>> t_slot->hpc_ops->get_adapter_status(t_slot, &value); /* Check if
>>>> slot is occupied */
>>>> - if (value && pciehp_force) {
>>>> + if (value && (pciehp_force || pciehp_passive)) {
>>>> rc = pciehp_enable_slot(t_slot);
>>>> if (rc) /* -ENODEV: shouldn't happen, but deal with it */
>>>> value = 0;
>> This code no longer runs in the pciehp_passive case. However, by the
>> looks of it it still does in the resume case - that probably wants
>> fixing.
>
> Thinking about this - you said that the problem occurs because
> pciehp_force=1 causes it to try to enable an already enabled slot, and
> then tries to power down the slot as a result? It sounds like this code
> should actually be checking whether the return value is ENODEV or
> EINVAL, and in the latter case not powering the slot down. That sounds
> like a separate bugfix that I'll send later on.
>

I think the root cause of this problem is the following line.

>>>> value = 0;

I can't understand why the 'value' is set to 0 when pciehp_enable_slot()
returns error. The 'value' here is representing whether the slot is
occupied or not. Even if pciehp_enable_slot() returns error, it doesn't
mean slot is not occupied. So I think it is clearly wrong thing that
changing 'value' to 0 from 1 here.

How about just ignore the return value from pciehp_enable_slot()? The
code would be as follows.

t_slot = pciehp_find_slot(ctrl, ctrl->slot_device_offset);
t_slot->hpc_ops->get_adapter_status(t_slot, &value);
if (value) {
if (pciehp_force)
pciehp_enable_slot(t_slot);
} else {
/* Power off the slot if not occupied, just in case */
if (POWER_CTRL(ctrl))
if (t_slot->hpc_ops->power_off_slot(t_slot))
goto err_out_free_ctrl_slots;
}

Thanks,
Kenji Kaneshige