On Tue, May 24, 2016 at 03:53:23PM +0300, Mika Westerberg wrote: > On Tue, May 24, 2016 at 07:23:57AM -0500, Bjorn Helgaas wrote: > > On Mon, May 23, 2016 at 04:50:15PM -0500, Bjorn Helgaas wrote: > > > [+cc Valdis, Dave] > > > > > > On Mon, May 23, 2016 at 03:00:42PM -0500, Bjorn Helgaas wrote: > > > > On Mon, May 23, 2016 at 11:20:48AM +0300, Mika Westerberg wrote: > > > > > When a PCI device is removed through sysfs interface the upstream bridge > > > > > (PCIe port) can be runtime suspended if it was the last device on that bus. > > > > > Now, if the bridge is in D3 we cannot find devices below the bridge > > > > > anymore. For example following fails to find the removed device again: > > > > > > > > > > # echo 1 > /sys/bus/pci/devices/0000:00:01.0/0000:01:00.0/remove > > > > > # echo 1 > /sys/bus/pci/devices/0000:00:01.0/rescan > > > > > > > > > > Where 0000:00:01.0 is the bridge device. > > > > > > > > > > In order to be able to rescan devices below the bridge add > > > > > pm_runtime_get_sync()/pm_runtime_put() calls to pci_scan_bridge(). This > > > > > should keep bridges powered on while their children devices are being > > > > > scanned. > > > > > > > > > > Reported-by: Peter Wu <peter@xxxxxxxxxxxxx> > > > > > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > > > > > > > This looks like basically the same idea as "ACPI / hotplug / PCI: > > > > Runtime resume bridge before rescan". > > > > > > > > The hotplug_event() path modified by that patch eventually calls > > > > pci_scan_bridge(): > > > > > > > > hotplug_event > > > > enable_slot > > > > pci_scan_bridge > > > > > > > > so this patch looks a little more general. Does it make "ACPI / > > > > hotplug / PCI: Runtime resume bridge before rescan" unnecessary? > > > > Can I just replace that patch with this one? > > > > > > I speculatively replaced "ACPI / hotplug / PCI: Runtime resume bridge > > > before rescan" with this one and pushed the result to > > > > > > https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/log/?h=pci/pm > > > > > > Please take a look, test it, and let me know if I need to add the ACPI > > > patch back. > > > > > > This branch also includes the fix for the lockdep splat reported by > > > Valdis. This is what I hope to get into v4.7-rc1. > > > > Ping? I'd like to ask Linus to pull this pci/pm branch before v4.7-rc1. > > It currently has these changes: > > > > 8b71f5652eea PCI: Add runtime PM support for PCIe ports > > af81f0fa638b PCI: Power on bridges before scanning new devices > > 9741a01c9f55 PCI: Put PCIe ports into D3 during suspend > > b3a63ff7baf1 PCI: Don't clear d3cold_allowed for PCIe ports > > Looks good to me. I've also tested those here and seems to work fine. I have tested these patches for some time now on top of v4.6 (just dropped the ACPI hotplug patch and re-tested just to be sure) and it works for nouveau, but only if that one is patched to avoid calling the device-specific Optimus method. Without that patch (WIP below, I plan to rebase it on a refactoring patch), the nvidia card stays disabled even after the bridge returns into D0: nouveau 0000:01:00.0: power state changed by ACPI to D0 nouveau 0000:01:00.0: Refused to change power state, currently in D3 nouveau 0000:01:00.0: restoring config space at offset 0x3c (was 0xffffffff, writing 0x1ff) nouveau 0000:01:00.0: restoring config space at offset 0x38 (was 0xffffffff, writing 0x0) nouveau 0000:01:00.0: restoring config space at offset 0x34 (was 0xffffffff, writing 0x60) nouveau 0000:01:00.0: restoring config space at offset 0x30 (was 0xffffffff, writing 0xdf000000) ... INFO: rcu_sched self-detected stall on CPU A workaround (until nouveau is fixed) is to disable runtime PM on the bridge (or on nouveau with nouveau.runpm=0): # echo on > /sys/bus/pci/devices/0000:00:01.0/power/control This was tested on a Clevo P651RA laptop (with acpi_osi="!Windows 2013", there is a weird PCIe PM issue for which I will fill a report later). Kind regards, Peter > > I dropped "ACPI / hotplug / PCI: Runtime resume bridge before rescan" > > on the assumption that "PCI: Power on bridges before scanning new > > devices" is sufficient to cover both the ACPI and the generic PCi > > rescan cases, but I'd like some reassurance about that. > > I agree with your reasoning that the patch should not be needed anymore. > However, I have the machine which needed that patch at home so I'm not > able to test it now. I'll do that later today when I get back home. > > One thing I noticed, though. When a bridge is transitioned to D0 we only > wait for 10ms which is requirement for PCI functions. However, PCI PM > specification 1.2 (chapter 4.2) requires that for buses to transition > from B2 to B0 we need to wait minimum of 50ms before accessing a > function on that bus. > > We even have PCI_PM_BUS_WAIT defined in include/linux/pci.h but it is > not used anywhere. Maybe it was not needed originally because we never > powered down bridges anyway but now when we do, I think it is good idea > to do what the spec requires. > > What do you think? We could add a separate patch doing something like > below to make sure the spec is followed. > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index e785dc260e72..b3b794caa380 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -2361,7 +2361,12 @@ void pci_pm_init(struct pci_dev *dev) > } > > dev->pm_cap = pm; > - dev->d3_delay = PCI_PM_D3_WAIT; > + /* > + * PCI PM 1.2 specification requires minimum of 50ms before any > + * function on the bus is accessed after the bus is transitioned > + * from B2 to B0. > + */ > + dev->d3_delay = pci_is_bridge(dev) ? PCI_PM_BUS_WAIT : PCI_PM_D3_WAIT; > dev->d3cold_delay = PCI_PM_D3COLD_WAIT; > dev->bridge_d3 = pci_bridge_d3_possible(dev); > dev->d3cold_allowed = true; --- diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c b/drivers/gpu/drm/nouveau/nouveau_acpi.c index cdf5227..531d6be 100644 --- a/drivers/gpu/drm/nouveau/nouveau_acpi.c +++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c @@ -45,6 +45,7 @@ static struct nouveau_dsm_priv { bool dsm_detected; bool optimus_detected; + bool use_pr3; acpi_handle dhandle; acpi_handle rom_handle; } nouveau_dsm_priv; @@ -246,6 +247,28 @@ static int nouveau_dsm_pci_probe(struct pci_dev *pdev) return retval; } +/* Windows 8/8.1/10 do not use DSM to put the device in D3cold state, + * instead it disables power resources on the parent PCIe port device. */ +static bool nouveau_check_pr3(struct pci_dev *dis_dev) +{ + acpi_handle parent_handle; + struct acpi_device *ad = NULL; + + if (ACPI_FAILURE(acpi_get_parent(nouveau_dsm_priv.dhandle, + &parent_handle))) { + pr_warn("Failed to obtain the parent device\n"); + return false; + } + + acpi_bus_get_device(parent_handle, &ad); + if (!ad) { + pr_warn("Failed to obtain an ACPI device for handle\n"); + return false; + } + + return ad->power.flags.power_resources; +} + static bool nouveau_dsm_detect(void) { char acpi_method_name[255] = { 0 }; @@ -253,6 +276,7 @@ static bool nouveau_dsm_detect(void) struct pci_dev *pdev = NULL; int has_dsm = 0; int has_optimus = 0; + int has_pr3 = 0; int vga_count = 0; bool guid_valid; int retval; @@ -271,8 +295,10 @@ static bool nouveau_dsm_detect(void) retval = nouveau_dsm_pci_probe(pdev); if (retval & NOUVEAU_DSM_HAS_MUX) has_dsm |= 1; - if (retval & NOUVEAU_DSM_HAS_OPT) + if (retval & NOUVEAU_DSM_HAS_OPT) { has_optimus = 1; + has_pr3 |= nouveau_check_pr3(pdev); + } } while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_3D << 8, pdev)) != NULL) { @@ -281,8 +307,10 @@ static bool nouveau_dsm_detect(void) retval = nouveau_dsm_pci_probe(pdev); if (retval & NOUVEAU_DSM_HAS_MUX) has_dsm |= 1; - if (retval & NOUVEAU_DSM_HAS_OPT) + if (retval & NOUVEAU_DSM_HAS_OPT) { has_optimus = 1; + has_pr3 |= nouveau_check_pr3(pdev); + } } /* find the optimus DSM or the old v1 DSM */ @@ -292,6 +320,10 @@ static bool nouveau_dsm_detect(void) printk(KERN_INFO "VGA switcheroo: detected Optimus DSM method %s handle\n", acpi_method_name); nouveau_dsm_priv.optimus_detected = true; + if (has_pr3) { + pr_info("detected PR3 support\n"); + nouveau_dsm_priv.use_pr3 = 1; + } ret = true; } else if (vga_count == 2 && has_dsm && guid_valid) { acpi_get_name(nouveau_dsm_priv.dhandle, ACPI_FULL_PATHNAME, @@ -321,7 +353,7 @@ void nouveau_register_dsm_handler(void) void nouveau_switcheroo_optimus_dsm(void) { u32 result = 0; - if (!nouveau_dsm_priv.optimus_detected) + if (!nouveau_dsm_priv.optimus_detected || nouveau_dsm_priv.use_pr3) return; nouveau_optimus_dsm(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_OPTIMUS_FLAGS, -- 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
