On Thursday, September 05, 2013 02:17:06 PM Lan Tianyu wrote: > 2013/9/5 Alex Williamson <alex.williamson@xxxxxxxxxx>: > > On Thu, 2013-09-05 at 01:35 +0200, Rafael J. Wysocki wrote: > >> 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. > > > > Here's the call path: > > > > [ 16.120824] [<ffffffff81627e6c>] dump_stack+0x55/0x76 > > [ 16.125979] [<ffffffff8162132e>] enable_slot+0x4ee/0x5e0 > > [ 16.131396] [<ffffffff813418fb>] ? trim_stale_devices+0x5b/0xf0 > > [ 16.137420] [<ffffffff81341b35>] acpiphp_check_bridge+0xd5/0x110 > > [ 16.143531] [<ffffffff81342acb>] hotplug_event+0x16b/0x260 > > [ 16.149115] [<ffffffff81072cd9>] ? process_one_work+0x189/0x540 > > [ 16.155136] [<ffffffff81342bf0>] hotplug_event_work+0x30/0x70 > > [ 16.160978] [<ffffffff81072d3b>] process_one_work+0x1eb/0x540 > > [ 16.166819] [<ffffffff81072cd9>] ? process_one_work+0x189/0x540 > > [ 16.172836] [<ffffffff8107353c>] worker_thread+0x11c/0x370 > > [ 16.178426] [<ffffffff81073420>] ? rescuer_thread+0x350/0x350 > > [ 16.184276] [<ffffffff8107b0ea>] kthread+0xea/0xf0 > > [ 16.189165] [<ffffffff8107b000>] ? kthread_create_on_node+0x160/0x160 > > [ 16.195700] [<ffffffff816395dc>] ret_from_fork+0x7c/0xb0 > > [ 16.201109] [<ffffffff8107b000>] ? kthread_create_on_node+0x160/0x160 > > > > The actual death of the serial console occurs in acpi_device_set_power() > > called from: > > > > enable_slot() > > acpiphp_bus_add() > > acpiphp_bus_trim() > > acpi_bus_trim() > > acpi_walk_namespace() > > acpi_bus_remove() > > acpi_device_unregister() > > acpi_device_set_power() > > > > I can't seem to get a path from the acpi devices in question there, so I > > have no idea what's getting trimmed here. It worries me quite a bit by > > introducing this trimming that apparently wasn't happening before > > though. Thanks, > > Hi Alex: > Could you apply the following patch and bootup with kernel param > "acpiphp.acpiphp_debug=1"? > I guess the patch can make serial port alive. It will not > be put into D3cold > during trimming. But I don't know why it doesn't work after being put > back to D0. Do we actually put it into D0 in acpi_bus_scan()? I don't think so. > So please attach output of acpidump and the dmesg if it can work. Thanks. > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index e763651..359b23d 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -1110,7 +1110,7 @@ static void acpi_device_unregister(struct > acpi_device *device) > * power resources the device depends on and turn off the ones that have > * no more references. > */ > - acpi_device_set_power(device, ACPI_STATE_D3_COLD); > + //acpi_device_set_power(device, ACPI_STATE_D3_COLD); > device->handle = NULL; > put_device(&device->dev); > } I don't think we should do the trimming in acpiphp_bus_add() at all. 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
