On 06/02/2015 06:31 PM, Prarit Bhargava wrote: > On 06/02/2015 04:44 PM, Bjorn Helgaas wrote: >> On Tue, Jun 02, 2015 at 01:54:18PM -0400, Prarit Bhargava wrote: >>> On 05/26/2015 12:07 PM, Bjorn Helgaas wrote: >> >>> ... >>> [ 1.546925] pci_bus 0000:00: root bus resource [bus 00-3e] >>> [ 1.552397] pci_bus 0000:00: root bus resource [io 0x0000-0x0cf7 window] >>> [ 1.559165] pci_bus 0000:00: root bus resource [io 0x0d00-0xffff window] >>> [ 1.565934] pci_bus 0000:00: root bus resource [mem 0x000a0000-0x000bffff window] >>> [ 1.573398] pci_bus 0000:00: root bus resource [mem 0x000d0000-0x000d3fff window] >>> [ 1.580861] pci_bus 0000:00: root bus resource [mem 0x000d4000-0x000d7fff window] >>> [ 1.588322] pci_bus 0000:00: root bus resource [mem 0x000d8000-0x000dbfff window] >>> [ 1.595784] pci_bus 0000:00: root bus resource [mem 0x000dc000-0x000dffff window] >>> [ 1.603246] pci_bus 0000:00: root bus resource [mem 0x000e0000-0x000e3fff window] >>> [ 1.610707] pci_bus 0000:00: root bus resource [mem 0x000e4000-0x000e7fff window] >>> [ 1.618170] pci_bus 0000:00: root bus resource [mem 0xb0000000-0xfeafffff window] >> >>> [ 1.637470] pci 0000:00:16.3: [8086:1e3d] type 00 class 0x070002 >>> [ 1.637486] pci 0000:00:16.3: reg 0x10: [io 0x70a0-0x70a7] >>> [ 1.637495] pci 0000:00:16.3: reg 0x14: [mem 0xb1580000-0xb1580fff] >> >>> [ 2.961417] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled >>> [ 2.988543] 00:04: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A >>> [ 3.016847] serial8250: ttyS2 at I/O 0x3e8 (irq = 4, base_baud = 115200) is a >>> 16550A >>> [ 3.045264] 0000:00:16.3: ttyS1 at I/O 0x70a0 (irq = 19, base_baud = 115200) >>> is a 16550A >> >>>> In this scenario, I assume the serial port device remains powered all the >>>> time, even while it is logically removed from the system, so when we >>>> re-enumerate and find the device, I would think its BARs would still >>>> contain whatever they had before, and since they are still valid, we should >>>> still use them. >>> >>> Nope. The device should go down as ttyS1 is not active. >> >> I'm talking about the 00:16.3 PCI device. I doubt there's anything that >> would remove power from it when you do the "echo 1 > remove". Of course, >> Linux will forget about it, and 00:16.3 shouldn't show up in lspci output, >> but from the device's point of view, nothing has really changed. When we >> rescan, we should find it just as we left it (it's possible we'd clear bits >> in the PCI_COMMAND register or something, but I'm not sure we even do >> that, and I'm pretty sure we don't clear out the BARs). >> >>>> So I think my expectation is the same as yours, and I don't know why it >>>> doesn't work that way. I assume the device actually *works* with the new >>>> resources, so it's not really broken in that sense, but it does bother me >>>> if we're changing something when we don't need to change it. >>> >>> Yep ... I think it's broken. Here's what I'm doing to down then rescan >>> the device. >>> >>> [root@intel-chiefriver-04 ~]# cd /sys/devices/pci0000\:00/0000\:00\:16.3 >>> [root@intel-chiefriver-04 0000:00:16.3]# echo 1 > remove >>> [root@intel-chiefriver-04 0000:00:16.3]# lspci | grep 16.3 >>> [root@intel-chiefriver-04 0000:00:16.3]# cd ../pci_bus/0000\:00/ >>> [root@intel-chiefriver-04 0000:00]# echo 1 > rescan >> >> The /sys/devices/pci0000:00/0000:00:16.3/ directory should disappear when >> you remove the device. In this case you were *inside* the directory when >> you did the remove, so your shell is holding a reference to it. But if you >> do this: >> >> # cd /sys/devices/pci0000:00 >> # echo 1 > 0000:00:16.3/remove >> # ls >> >> you should not see the 0000:00:16.3 directory any more. >> >>> and the console contains >>> >>> [ 353.212980] pci 0000:00:16.3: [8086:1e3d] type 00 class 0x070002 >>> [ 353.231163] pci 0000:00:16.3: BAR 1: assigned [mem 0xb1520000-0xb1520fff] >>> [ 353.237937] pci 0000:00:16.3: BAR 0: assigned [io 0x1018-0x101f] >> >> There should be some more output here. I usually boot with >> "ignore_loglevel" to make sure I see everything. >> Geez ... that's a terrible way to find a bug in my system setup script. :/ ignore_loglevel was NOT set and that's why I wasn't seeing additional output. It looks like the rescan is picking up the same addresses as before and we're getting stuck in the serial code. Sorry for the noise Bjorn, P. -- 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
