On Tue, Jul 10, 2012 at 5:12 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: > On Tue, Jul 10, 2012 at 3:56 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: >> On Sat, Jun 23, 2012 at 1:42 AM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: >>> If surprise removal is not supported, that event get dropped later. >>> So there is no point to enable that. >>> >>> Also some sick chipset have those bit flip around when the card is not present. >>> and make log full of useless warning. >> >> HP_SUPR_RM tests the Slot Capabilities "Hot-Plug Surprise" bit, which >> indicates that an adapter might be *removed* without prior >> notification (sec 7.8.9). >> >> PCI_EXP_SLTCTL_PDCE is the Slot Control "Presence Detect Changed >> Enable" bit, which enables interrupts for any change in the Slot >> Status "Presence Detect State", i.e., we may get interrupts for either >> add or remove events. >> >> In interrupt_event_handler(), we drop both add and remove events if >> !HP_SUPR_RM(). Specifically, we drop *add* events if surprise >> *removal* isn't supported. That seems strange -- just from reading >> the spec, it seems that a surprise *add* could occur even if the >> "Hot-Plug Surprise" bit is not set. > > Interesting, that means after card is plugged in, we don't need to > press attention button to bring > it online. > > And other oses like windows and solaris do need to press the button > like current linux doing. The attention button is apparently optional, depending on the form factor. I would guess that on a platform with no attention button and Hot-Plug Surprise == 0, Linux would be unable to do a hot-add. >> So I'm not convinced that we should even bother looking at the >> "Hot-Plug Surprise" bit... Maybe we'd be better off if we just >> removed that HP_SUPR_RM() test in interrupt_event_handler() and always >> called handle_surprise_event(). > > Ah, that means some system with chip problem will keep feeding > pciehp_wq with pciehp_disable_slot and pciehp_enable_slot. > > Anyway please drop this patch now. Dropped. -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
