[PATCH 6.12 554/567] PCI: brcmstb: Fix disabling L0s capability

Greg Kroah-Hartman
2026-01-06T17:44:58Z

From: Jim Quinlan <james.quinlan@broadcom.com>

[ Upstream commit 9583f9d22991d2cfb5cc59a2552040c4ae98d998 ]

caab002d5069 ("PCI: brcmstb: Disable L0s component of ASPM if requested")
set PCI_EXP_LNKCAP_ASPM_L1 and (optionally) PCI_EXP_LNKCAP_ASPM_L0S in
PCI_EXP_LNKCAP (aka PCIE_RC_CFG_PRIV1_LINK_CAPABILITY in brcmstb).

But instead of using PCI_EXP_LNKCAP_ASPM_L1 and PCI_EXP_LNKCAP_ASPM_L0S
directly, it used PCIE_LINK_STATE_L1 and PCIE_LINK_STATE_L0S, which are
Linux-created values that only coincidentally matched the PCIe spec.
b478e162f227 ("PCI/ASPM: Consolidate link state defines") later changed
them so they no longer matched the PCIe spec, so the bits ended up in the
wrong place in PCI_EXP_LNKCAP.

Use PCI_EXP_LNKCAP_ASPM_L0S to clear L0s support when there's an
'aspm-no-l0s' property. Rely on brcmstb hardware to advertise L0s and/or
L1 support otherwise.

Fixes: caab002d5069 ("PCI: brcmstb: Disable L0s component of ASPM if requested")
Reported-by: Bjorn Helgaas <bhelgaas@google.com>
Closes: https://lore.kernel.org/linux-pci/20250925194424.GA2197200@bhelgaas
Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
[mani: reworded subject and description, added closes tag and CCed stable]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20251003170436.1446030-1-james.quinlan@broadcom.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/pci/controller/pcie-brcmstb.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -47,7 +47,6 @@

#define PCIE_RC_CFG_PRIV1_LINK_CAPABILITY 0x04dc
#define PCIE_RC_CFG_PRIV1_LINK_CAPABILITY_MAX_LINK_WIDTH_MASK 0x1f0
-#define PCIE_RC_CFG_PRIV1_LINK_CAPABILITY_ASPM_SUPPORT_MASK 0xc00

#define PCIE_RC_CFG_PRIV1_ROOT_CAP 0x4f8
#define PCIE_RC_CFG_PRIV1_ROOT_CAP_L1SS_MODE_MASK 0xf8
@@ -1029,7 +1028,7 @@ static int brcm_pcie_setup(struct brcm_p
void __iomem *base = pcie->base;
struct pci_host_bridge *bridge;
struct resource_entry *entry;
- u32 tmp, burst, aspm_support, num_lanes, num_lanes_cap;
+ u32 tmp, burst, num_lanes, num_lanes_cap;
u8 num_out_wins = 0;
int num_inbound_wins = 0;
int memc, ret;
@@ -1129,12 +1128,9 @@ static int brcm_pcie_setup(struct brcm_p

/* Don't advertise L0s capability if 'aspm-no-l0s' */
- aspm_support = PCIE_LINK_STATE_L1;
- if (!of_property_read_bool(pcie->np, "aspm-no-l0s"))
- aspm_support |= PCIE_LINK_STATE_L0S;
tmp = readl(base + PCIE_RC_CFG_PRIV1_LINK_CAPABILITY);
- u32p_replace_bits(&tmp, aspm_support,
- PCIE_RC_CFG_PRIV1_LINK_CAPABILITY_ASPM_SUPPORT_MASK);
+ if (of_property_read_bool(pcie->np, "aspm-no-l0s"))
+ tmp &= ~PCI_EXP_LNKCAP_ASPM_L0S;
writel(tmp, base + PCIE_RC_CFG_PRIV1_LINK_CAPABILITY);

/* 'tmp' still holds the contents of PRIV1_LINK_CAPABILITY */