Hi, On Fri, Sep 13, 2024 at 02:00:58PM +0800, Kai-Heng Feng wrote: > On Fri, Sep 13, 2024 at 12:57 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > > > [+cc Rafael] > > > > On Thu, Sep 12, 2024 at 11:00:43AM +0800, Kai-Heng Feng wrote: > > > On Thu, Sep 12, 2024 at 3:05 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > > > On Fri, Jul 12, 2024 at 02:24:11PM +0800, Kai-Heng Feng wrote: > > > > > Some laptops wake up after poweroff when HP Thunderbolt Dock G4 is > > > > > connected. > > > > > > > > > > The following error message can be found during shutdown: > > > > > pcieport 0000:00:1d.0: AER: Correctable error message received from 0000:09:04.0 > > > > > pcieport 0000:09:04.0: PCIe Bus Error: severity=Correctable, type=Data Link Layer, (Receiver ID) > > > > > pcieport 0000:09:04.0: device [8086:0b26] error status/mask=00000080/00002000 > > > > > pcieport 0000:09:04.0: [ 7] BadDLLP > > > > > > > > > > Calling aer_remove() during shutdown can quiesce the error message, > > > > > however the spurious wakeup still happens. > > > > > > > > > > The issue won't happen if the device is in D3 before system shutdown, so > > > > > putting device to low power state before shutdown to solve the issue. > > > > > > > > > > I don't have a sniffer so this is purely guesswork, however I believe > > > > > putting device to low power state it's the right thing to do. > > > > > > > > My objection here is that we don't have an explanation of why this > > > > should matter or a pointer to any spec language about this situation, > > > > so it feels a little bit random. > > > > > > I have the same feeling too. The PCIe spec doesn't specify what's the > > > correct power state for shutdown. > > > So we can only "logically" think the software should put devices to > > > low power state during shutdown. > > > > > > > I suppose the problem wouldn't happen if AER interrupts were disabled? > > > > We already do disable them in aer_suspend(), but maybe that's not used > > > > in the shutdown path? > > > > > > That was my first thought, so I modified pcie_port_shutdown_service() > > > to disable AER interrupt. > > > That approach didn't work though. > > > > > > > My understanding is that .shutdown() should turn off device interrupts > > > > and stop DMA. So maybe we need an aer_shutdown() that disables > > > > interrupts? > > > > > > Logically we should do that. However that approach doesn't solve this issue. > > > > I'm not completely clear on the semantics of the .shutdown() > > interface. The doc at > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/device/driver.h?id=v6.10#n73 > > says "@shutdown: Called at shut-down time to quiesce the device" > > > > Turning off device interrupts and DMA *would* fit within the idea of > > quiescing the device. Does that also include changing the device > > power state? I dunno. The power state isn't *mentioned* in the > > .shutdown() context, while it *is* mentioned for .suspend(). > > IMO putting a device to low power also qualifies as "quiesce the device". > > > > > IIUC, this patch and commit log uses "shutdown" to refer to a > > system-wide *poweroff*, which is a different concept despite using the > > same "shutdown" name. > > For ACPI based system, there are .suspend for S3/s2idle, .poweroff for > S4, and .shutdown for S5. > Unless we want to introduce a new callback for S5, I think the concept > is quite similar. > > For DT based system, the OS should also perform the same thing, as > there's no firmware to cleanup the power state. > > We can also move .shutdown to be part of pm_ops, but I don't think > it's necessary, > > > > > So should the system poweroff procedure use .suspend()? Should it use > > both .shutdown() and .suspend()? I think it only uses .shutdown() > > today: > > > > kernel_power_off > > kernel_shutdown_prepare(SYSTEM_POWER_OFF) > > device_shutdown > > while (!list_empty(&devices_kset->list)) > > dev->bus->shutdown(dev) > > pci_device_shutdown > > > > There are several driver .shutdown() methods that do things like this: > > > > e1000_shutdown > > if (system_state == SYSTEM_POWER_OFF) > > pci_set_power_state(pdev, PCI_D3hot) > > > > Maybe that's the right thing and should be done by the PCI core, which > > is similar to what you propose here. But I think it muddies the > > definition of .shutdown() a bit by mixing in power management stuff. > > Do you think adding a new "low power state" callback to be called > after .shutdown a good idea? > That would make the concept of .shutdown different to .suspend and > .poweroff. I personally see .suspend, .poweroff and .shutdown the same > action but target different power states. I don't mean to confuse you guys but with this one too, I wonder if you tried to "disable" the device instead of putting it into D3? On another thread (Mario at least is aware of this) I mentioned that our PCIe SV folks identified a couple issues in Linux implementation around power management and one thing that we are missing is to disable I/O and MMIO upon entering D3. I know this is about entering S5 (power off) but I wonder if simply disabling the device (I/O, MMIO and bus mastering) could stop it from waking up? To my understanding this can be interpreted as quiesce too :) Something like the below patch (it also includes the runtime suspend path which should not matter here. This is the similar patch I shared in another thread). diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index f412ef73a6e4..79406814699d 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -514,11 +514,9 @@ static void pci_device_shutdown(struct device *dev) * If this is a kexec reboot, turn off Bus Master bit on the * device to tell it to not continue to do DMA. Don't touch * devices in D3cold or unknown states. - * If it is not a kexec reboot, firmware will hit the PCI - * devices with big hammer and stop their DMA any way. */ - if (kexec_in_progress && (pci_dev->current_state <= PCI_D3hot)) - pci_clear_master(pci_dev); + if (pci_dev->current_state <= PCI_D3hot) + pci_disable_device(pci_dev); } #ifdef CONFIG_PM_SLEEP @@ -1332,6 +1330,7 @@ static int pci_pm_runtime_suspend(struct device *dev) if (!pci_dev->state_saved) { pci_save_state(pci_dev); + pci_pm_default_suspend(pci_dev); pci_finish_runtime_suspend(pci_dev); } diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index ffaaca0978cb..91f4e7a03c94 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2218,6 +2218,13 @@ static void do_pci_disable_device(struct pci_dev *dev) pci_command &= ~PCI_COMMAND_MASTER; pci_write_config_word(dev, PCI_COMMAND, pci_command); } + /* + * PCI PM 1.2 sec 8.2.2 says that when a function is put into D3 + * the OS needs to disable I/O and MMIO space in addition to bus + * mastering so do that here. + */ + pci_command &= ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY); + pci_write_config_word(dev, PCI_COMMAND, pci_command); pcibios_disable_device(dev); }
