On Wednesday, September 04, 2013 05:12:14 PM Alex Williamson wrote: > On Thu, 2013-09-05 at 00:54 +0200, Rafael J. Wysocki wrote: > > On Wednesday, September 04, 2013 02:36:34 PM Alex Williamson wrote: > > > On Thu, 2013-07-18 at 01:32 +0200, Rafael J. Wysocki wrote: > > > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > > > > > > > The current implementation of acpiphp_check_bridge() is pretty dumb: > > > > - It enables a slot if it's not enabled and the slot status is > > > > ACPI_STA_ALL. > > > > - It disables a slot if it's enabled and the slot status is not > > > > ACPI_STA_ALL. > > > > > > > > This behavior is not sufficient to handle the Thunderbolt daisy > > > > chaining case properly, however, because in that case the bus > > > > behind the already enabled slot needs to be rescanned for new > > > > devices. > > > > > > > > For this reason, modify acpiphp_check_bridge() so that slots are > > > > disabled and stopped if they are not in the ACPI_STA_ALL state. > > > > > > > > For slots in the ACPI_STA_ALL state, devices behind them that don't > > > > respond are trimmed using a new function, trim_stale_devices(), > > > > introduced specifically for this purpose. That function walks > > > > the given bus and checks each device on it. If the device doesn't > > > > respond, it is assumed to be gone and is removed. > > > > > > > > Once all of the stale devices directy behind the slot have been > > > > removed, acpiphp_check_bridge() will start looking for new devices > > > > that might have appeared on the given bus. It will do that even if > > > > the slot is already enabled (SLOT_ENABLED is set for it). > > > > > > > > In addition to that, make the bus check notification ignore > > > > SLOT_ENABLED and go for enable_device() directly if bridge is NULL, > > > > so that devices behind the slot are re-enumerated in that case too. > > > > > > > > This change is based on earlier patches from Kirill A Shutemov > > > > and Mika Westerberg. > > > > > > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > > > Tested-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > > > --- > > > > > > FYI, git bisect landed on this patch as the cause of my serial console > > > dying on current upstream. Further debugging to come... Thanks, > > > > Well, sorry about that. > > > > What exactly do you mean by "dying"? > > Sorry, I was hoping to have more details quickly, but it's been a pain > to debug. By dying I mean serial console output suddenly stops during > kernel boot and nothing more comes out of it until after the system is > rebooted. The problem happens when acpiphp_check_bridge() calls > enable_slot(). The serial console dies somewhere down in > acpiphp_bus_trim(). I think this is happening on the 00:1f ISA bridge, > so there's a good chance the serial ports are described as somewhere > under there. Can you please check if that is the acpiphp_bus_trim() called by acpiphp_bus_add() or the other one called from trim_stale_devices()? Just add a dump_stack() or WARN_ON(1) to trim_stale_devices() next to the acpiphp_bus_trim() call and see if that triggers. I *think* it's the one in acpiphp_bus_add(), but it won't hurt to verify that. Thanks, Rafael -- 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
