From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lan Tianyu Subject: Re: [PATCH 25/30] ACPI / hotplug / PCI: Check for new devices on enabled slots Date: Thu, 5 Sep 2013 09:11:51 -0400 Message-ID: References: <26431283.HJCKsss0rt@vostro.rjw.lan> <1378352279.3246.183.camel@ul30vt.home> <81108254.GSTBHzP5cb@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: <81108254.GSTBHzP5cb@vostro.rjw.lan> Sender: linux-kernel-owner@vger.kernel.org To: "Rafael J. Wysocki" Cc: Alex Williamson , ACPI Devel Maling List , Bjorn Helgaas , LKML , Linux PCI , Yinghai Lu , Jiang Liu , Mika Westerberg , "Kirill A. Shutemov" List-Id: linux-acpi@vger.kernel.org 2013/9/5 Rafael J. Wysocki : > On Thursday, September 05, 2013 02:17:06 PM Lan Tianyu wrote: >> 2013/9/5 Alex Williamson : >> > 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 >> >> > > > > >> >> > > > > 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 >> >> > > > > Tested-by: Mika Westerberg >> >> > > > > --- >> >> > > > >> >> > > > 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] [] dump_stack+0x55/0x76 >> > [ 16.125979] [] enable_slot+0x4ee/0x5e0 >> > [ 16.131396] [] ? trim_stale_devices+0x5b/0xf0 >> > [ 16.137420] [] acpiphp_check_bridge+0xd5/0x110 >> > [ 16.143531] [] hotplug_event+0x16b/0x260 >> > [ 16.149115] [] ? process_one_work+0x189/0x540 >> > [ 16.155136] [] hotplug_event_work+0x30/0x70 >> > [ 16.160978] [] process_one_work+0x1eb/0x540 >> > [ 16.166819] [] ? process_one_work+0x189/0x540 >> > [ 16.172836] [] worker_thread+0x11c/0x370 >> > [ 16.178426] [] ? rescuer_thread+0x350/0x350 >> > [ 16.184276] [] kthread+0xea/0xf0 >> > [ 16.189165] [] ? kthread_create_on_node+0x160/0x160 >> > [ 16.195700] [] ret_from_fork+0x7c/0xb0 >> > [ 16.201109] [] ? 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. > Hi Rafael: I mean the code in the acpiphp_bus_add(). After trimming and acpi bus scan handle, the device will be put back to D0 if acpi_bus_get_device() return acpi device. So I thought the serial port is put back to D0. >> 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. Yes, I agree. > > Thanks, > Rafael > -- Best regards Tianyu Lan