PCI: dwc: Use common D3cold eligibility helper in suspend path

Previously, the driver skipped putting the link into L2 and device state in
D3cold whenever L1 ASPM was enabled, since some devices (e.g. NVMe) expect
low resume latency and may not tolerate deeper power states. However, such
devices typically remain in D0 and are already covered by the new helper's
requirement that all endpoints be in D3hot before the devices under host
bridge may enter D3cold.

Replace the local L1/L1SS-based check in dw_pcie_suspend_noirq() with the
shared pci_host_common_d3cold_possible() helper to decide whether the
devices under host bridge can safely transition to D3cold.

In addition, propagate PME-from-D3cold capability information from the
helper and record it in skip_pwrctrl_off. Some devices (e.g. M.2 cards
without auxiliary power) cannot send PME when the main power is removed,
even if they advertise PME-from-D3cold support. This allows controller
power-off to be skipped when required to preserve wakeup functionality.

While at it, update the 'dw_pcie::suspended' flag in dw_pcie_resume_noirq()
only after the PCIe link resumes successfully, to avoid marking the
controller as active when link resume fails.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
[mani: commit log and added TODO to query Vaux]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20260429-d3cold-v5-4-89e9735b9df6@oss.qualcomm.com

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index c9517a34883686a37d63b33671dcedd544ac07da..cffb34f6f3a9ec602f401c074588f76e0d15fe2b 100644 (file)
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -16,9 +16,11 @@
 #include <linux/msi.h>
 #include <linux/of_address.h>
 #include <linux/of_pci.h>
+#include <linux/pci.h>
 #include <linux/pci_regs.h>
 #include <linux/platform_device.h>
 
+#include "../pci-host-common.h"
 #include "../../pci.h"
 #include "pcie-designware.h"
 
@@ -1218,18 +1220,14 @@ static int dw_pcie_pme_turn_off(struct dw_pcie *pci)
 
 int dw_pcie_suspend_noirq(struct dw_pcie *pci)
 {
-       u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+       bool pme_capable = false;
        int ret = 0;
        u32 val;
 
        if (!dw_pcie_link_up(pci))
                goto stop_link;
 
-       /*
-        * If L1SS is supported, then do not put the link into L2 as some
-        * devices such as NVMe expect low resume latency.
-        */
-       if (dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_ASPM_L1)
+       if (!pci_host_common_d3cold_possible(pci->pp.bridge, &pme_capable))
                return 0;
 
        if (pci->pp.ops->pme_turn_off) {
@@ -1273,6 +1271,15 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
        udelay(1);
 
 stop_link:
+       /*
+        * TODO: "pme_capable" means some downstream device is wakeup-
+        * enabled and is capable of generating PME from D3cold, which
+        * requires auxiliary power.  Instead of always skipping power off
+        * if PME is supported from D3cold, query the pwrctrl core and skip
+        * power off only if device supports PME from D3cold and Vaux is
+        * not supported.
+        */
+       pci->pp.skip_pwrctrl_off = pme_capable;
        dw_pcie_stop_link(pci);
        if (pci->pp.ops->deinit)
                pci->pp.ops->deinit(&pci->pp);
@@ -1290,8 +1297,6 @@ int dw_pcie_resume_noirq(struct dw_pcie *pci)
        if (!pci->suspended)
                return 0;
 
-       pci->suspended = false;
-
        if (pci->pp.ops->init) {
                ret = pci->pp.ops->init(&pci->pp);
                if (ret) {
@@ -1313,6 +1318,8 @@ int dw_pcie_resume_noirq(struct dw_pcie *pci)
        if (pci->pp.ops->post_init)
                pci->pp.ops->post_init(&pci->pp);
 
+       pci->suspended = false;
+
        return 0;
 
 err_stop_link:

diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 3e69ef60165b0e58d8f69edcc2abf48485b69a82..e759c5c7257e52926628e4c19e10412e2d005008 100644 (file)
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -450,6 +450,7 @@ struct dw_pcie_rp {
        bool                    ecam_enabled;
        bool                    native_ecam;
        bool                    skip_l23_ready;
+       bool                    skip_pwrctrl_off;
 };
 
 struct dw_pcie_ep_ops {