On Tue, May 24, 2016 at 11:38:48AM -0500, Bjorn Helgaas wrote: > On Tue, May 24, 2016 at 04:27:44PM +0200, Peter Wu wrote: > > 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. > > I assume this nouveau issue is a driver problem unrelated to the > pci/pm changes, and it wouldn't make any difference if I included the > ACPI hotplug patch. Right? This is a nouveau-specific driver problem that is triggered by the adding runtime PM support for PCIe ports. > > 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). > > This seems like a pretty significant problem: if we enable runtime PM > on bridges by default, and Nvidia cards stay disabled when the bridge > returns to D0, that sounds like a bad regression. I don't think I > could ask Linus to pull these changes with a known issue like that. > Or am I misunderstanding something? That would indeed be a regression, please see this nouveau patch series for a suggestion: https://lists.freedesktop.org/archives/nouveau/2016-May/025116.html By the way, there is also currently a RPM refcounting issue in nouveau (possibly fixed by https://lists.freedesktop.org/archives/nouveau/2016-May/025107.html) which resulted in the following problem: 1. Initially RPM refcount is 1 when no driver is loaded for a device. 2. Load nouveau which will RPM suspend the device. refcount becomes 0. 3. Unload nouveau (bug: refcount stays 0). 4. As a result, the PCIe ports are runtime suspended (should probably not happen as there is no bound driver). 5. When nouveau is loaded again, the power resources are enabled again, *but* it does not put the device into D0 (it expected that this was already the case). (with ACPI debugging on I see that _PS0 is not called). 6. As a result, reading registers failed, "unknown chipset (ffffffff)" is printed to dmesg and the probe fails. (Maybe the PCI core should have a WARN when the RPM is "auto" and the refcount drops below 1 after remove is called with no driver left?) Kind regards, Peter Wu > > --- > > 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
