Re: [PATCH v22] PCI: Avoid D3 at suspend for AMD PCIe root ports w/ USB4 controllers

Mario Limonciello <mario.limonciello@xxxxxxx> · Thu, 5 Oct 2023 13:20:24 -0500

On 10/5/2023 13:14, Bjorn Helgaas wrote:
On Wed, Oct 04, 2023 at 09:49:59AM -0500, Mario Limonciello wrote:
Iain reports that USB devices can't be used to wake a Lenovo Z13 from
suspend.  This occurs because on some AMD platforms, even though the Root
Ports advertise PME_Support for D3hot and D3cold, they don't handle PME
messages and generate wakeup interrupts from those states when amd-pmc has
put the platform in a hardware sleep state.

Iain reported this on an AMD Rembrandt platform, but it also affects
Phoenix SoCs.  On Iain's system, a USB4 router below the affected Root Port
generates the PME. To avoid this issue, disable D3 for the root port
associated with USB4 controllers at suspend time.

Restore D3 support at resume so that it can be used by runtime suspend.
The amd-pmc driver doesn't put the platform in a hardware sleep state for
runtime suspend, so PMEs work as advertised.

Cc: stable@xxxxxxxxxxxxxxx
Link: https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/platform-design-for-modern-standby#low-power-core-silicon-cpu-soc-dram [1]
Fixes: 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend")
Reported-by: Iain Lane <iain@xxxxxxxxxxxxxxxxxxx>
Closes: https://forums.lenovo.com/t5/Ubuntu/Z13-can-t-resume-from-suspend-with-external-USB-keyboard/m-p/5217121
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>

Applied to pci/pm for v6.7, thanks for all your patience!


Thanks!  🎉

Unless you have a strong opposition I plan to also work out a series 
that takes some elements from earlier versions of the series and allows 
SoCs to "opt-in" to using constraints as an alternative for the policy 
decisions.

This wouldn't replace these quirks.  The intent would be that "follow on 
SoCs" that haven't launched and would otherwise need to keep adding to 
this quirk list can instead opt-in via that.  It would make the policy 
more closely follow how the Windows ecosystem works too.

I tweaked the commit log a bit to make it clearer that it only affects
USB4 devices and expand on the amd-pmc connection.  I also dropped the
microsoft.com link because I didn't see anything there that seemed
directly related to this patch:

     PCI: Avoid PME from D3hot/D3cold for AMD Rembrandt and Phoenix USB4
     
     Iain reports that USB devices can't be used to wake a Lenovo Z13 from
     suspend.  This occurs because on some AMD platforms, even though the Root
     Ports advertise PME_Support for D3hot and D3cold, wakeup events from
     devices on a USB4 controller don't result in wakeup interrupts from the
     Root Port when amd-pmc has put the platform in a hardware sleep state.
     
     If amd-pmc will be involved in the suspend, remove D3hot and D3cold from
     the PME_Support mask of Root Ports above USB4 controllers so we avoid those
     states if we need wakeups.
     
     Restore D3 support at resume so that it can be used by runtime suspend.
     
     This affects both AMD Rembrandt and Phoenix SoCs.
     
     "pm_suspend_target_state == PM_SUSPEND_ON" means we're doing runtime
     suspend, and amd-pmc will not be involved.  In that case PMEs work as
     advertised in D3hot/D3cold, so we don't need to do anything.
     
     Note that amd-pmc is technically optional, and there's no need for this
     quirk if it's not present, but we assume it's always present because power
     consumption is so high without it.
     
     Fixes: 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend")
     Link: https://lore.kernel.org/r/20231004144959.158840-1-mario.limonciello@xxxxxxx
     Reported-by: Iain Lane <iain@xxxxxxxxxxxxxxxxxxx>
     Closes: https://forums.lenovo.com/t5/Ubuntu/Z13-can-t-resume-from-suspend-with-external-USB-keyboard/m-p/5217121
     Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
     Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
     Cc: stable@xxxxxxxxxxxxxxx
---
v21->v22:
  * Back to PME to avoid implications for wakeup (Bjorn)
  * This is the submission that Bjorn sent in the mailing in response to v21.  It
    tests well, so Bjorn please add a Co-Developed-by/Signed-off-by for your
    self if you feel it's appropriate.
v20-v21:
  * Rewrite commit message, lifting most of what Bjorn clipped down to on v20.
  * Use pci_d3cold_disable()/pci_d3cold_enable() instead
  * Do the quirk on the USB4 controller instead of RP->USB->RP
---
  drivers/pci/quirks.c | 57 ++++++++++++++++++++++++++++++++++++++++++++
  1 file changed, 57 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index eeec1d6f9023..4b601b1c0830 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -6188,3 +6188,60 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x9a31, dpc_log_size);
  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_XILINX, 0x5020, of_pci_make_dev_node);
  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_XILINX, 0x5021, of_pci_make_dev_node);
  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_REDHAT, 0x0005, of_pci_make_dev_node);
+
+#ifdef CONFIG_SUSPEND
+/*
+ * Root Ports on some AMD SoCs advertise PME_Support for D3hot and D3cold, but
+ * if the SoC is put into a hardware sleep state by the amd-pmc driver, the
+ * Root Ports don't generate wakeup interrupts for USB devices.
+ *
+ * When suspending, remove D3hot and D3cold from the PME_Support advertised
+ * by the Root Port so we don't use those states if we're expecting wakeup
+ * interrupts.  Restore the advertised PME_Support when resuming.
+ */
+static void amd_rp_pme_suspend(struct pci_dev *dev)
+{
+	struct pci_dev *rp;
+
+	/*
+	 * PM_SUSPEND_ON means we're doing runtime suspend, which means
+	 * amd-pmc will not be involved so PMEs during D3 work as advertised.
+	 *
+	 * The PMEs *do* work if amd-pmc doesn't put the SoC in the hardware
+	 * sleep state, but we assume amd-pmc is always present.
+	 */
+	if (pm_suspend_target_state == PM_SUSPEND_ON)
+		return;
+
+	rp = pcie_find_root_port(dev);
+	if (!rp->pm_cap)
+		return;
+
+	rp->pme_support &= ~((PCI_PM_CAP_PME_D3hot|PCI_PM_CAP_PME_D3cold) >>
+				    PCI_PM_CAP_PME_SHIFT);
+	dev_info_once(&rp->dev, "quirk: disabling D3cold for suspend\n");
+}
+
+static void amd_rp_pme_resume(struct pci_dev *dev)
+{
+	struct pci_dev *rp;
+	u16 pmc;
+
+	rp = pcie_find_root_port(dev);
+	if (!rp->pm_cap)
+		return;
+
+	pci_read_config_word(rp, rp->pm_cap + PCI_PM_PMC, &pmc);
+	rp->pme_support = FIELD_GET(PCI_PM_CAP_PME_MASK, pmc);
+}
+/* Rembrandt (yellow_carp) */
+DECLARE_PCI_FIXUP_SUSPEND(PCI_VENDOR_ID_AMD, 0x162e, amd_rp_pme_suspend);
+DECLARE_PCI_FIXUP_RESUME(PCI_VENDOR_ID_AMD, 0x162e, amd_rp_pme_resume);
+DECLARE_PCI_FIXUP_SUSPEND(PCI_VENDOR_ID_AMD, 0x162f, amd_rp_pme_suspend);
+DECLARE_PCI_FIXUP_RESUME(PCI_VENDOR_ID_AMD, 0x162f, amd_rp_pme_resume);
+/* Phoenix (pink_sardine) */
+DECLARE_PCI_FIXUP_SUSPEND(PCI_VENDOR_ID_AMD, 0x1668, amd_rp_pme_suspend);
+DECLARE_PCI_FIXUP_RESUME(PCI_VENDOR_ID_AMD, 0x1668, amd_rp_pme_resume);
+DECLARE_PCI_FIXUP_SUSPEND(PCI_VENDOR_ID_AMD, 0x1669, amd_rp_pme_suspend);
+DECLARE_PCI_FIXUP_RESUME(PCI_VENDOR_ID_AMD, 0x1669, amd_rp_pme_resume);
+#endif /* CONFIG_SUSPEND */
--
2.34.1








