[PATCH] PCI: qcom: Clear Attention Button Present in Slot Capabilities

[Qiang Yu]

Qcom PCIe Root Ports advertise the Attention Button Present (ABP) bit in
the Slot Capabilities register, but the slots have no attention button.

When ABP is set, pcie_enable_notification() in the pciehp driver enables
the Attention Button Pressed interrupt (ABPE) and leaves the Presence
Detect Changed interrupt (PDCE) disabled. As a result, presence detect
changes are never reported and surprise hot-plug detection that relies on
Presence Detect Changed events does not work.

While at it, rename qcom_pcie_set_slot_nccs() to qcom_pcie_set_slot_cap()
since it now programs more than just the NCCS field.

Signed-off-by: Qiang Yu <qiang.yu@xxxxxxxxxxxxxxxx>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index b193c989b2b8..89c2d4cb1fbe 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -358,7 +358,7 @@ static void qcom_pcie_clear_aspm_l0s(struct dw_pcie *pci)
 	dw_pcie_dbi_ro_wr_dis(pci);
 }
 
-static void qcom_pcie_set_slot_nccs(struct dw_pcie *pci)
+static void qcom_pcie_set_slot_cap(struct dw_pcie *pci)
 {
 	u16 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
 	u32 val;
@@ -372,6 +372,11 @@ static void qcom_pcie_set_slot_nccs(struct dw_pcie *pci)
 	 */
 	val = readl(pci->dbi_base + offset + PCI_EXP_SLTCAP);
 	val |= PCI_EXP_SLTCAP_NCCS;
+	/*
+	 * Qcom PCIe Root Ports do not support Attention Button, so clear
+	 * Attention Button Present in Slot Capabilities.
+	 */
+	val &= ~PCI_EXP_SLTCAP_ABP;
 	writel(val, pci->dbi_base + offset + PCI_EXP_SLTCAP);
 
 	dw_pcie_dbi_ro_wr_dis(pci);
@@ -580,7 +585,7 @@ static int qcom_pcie_post_init_2_1_0(struct qcom_pcie *pcie)
 	writel(CFG_BRIDGE_SB_INIT,
 	       pci->dbi_base + AXI_MSTR_RESP_COMP_CTRL1);
 
-	qcom_pcie_set_slot_nccs(pcie->pci);
+	qcom_pcie_set_slot_cap(pcie->pci);
 
 	return 0;
 }
@@ -660,7 +665,7 @@ static int qcom_pcie_post_init_1_0_0(struct qcom_pcie *pcie)
 		writel(val, pcie->parf + PARF_AXI_MSTR_WR_ADDR_HALT);
 	}
 
-	qcom_pcie_set_slot_nccs(pcie->pci);
+	qcom_pcie_set_slot_cap(pcie->pci);
 
 	return 0;
 }
@@ -759,7 +764,7 @@ static int qcom_pcie_post_init_2_3_2(struct qcom_pcie *pcie)
 	val |= EN;
 	writel(val, pcie->parf + PARF_AXI_MSTR_WR_ADDR_HALT_V2);
 
-	qcom_pcie_set_slot_nccs(pcie->pci);
+	qcom_pcie_set_slot_cap(pcie->pci);
 
 	return 0;
 }
@@ -1078,7 +1083,7 @@ static int qcom_pcie_post_init_2_7_0(struct qcom_pcie *pcie)
 		writel(WR_NO_SNOOP_OVERRIDE_EN | RD_NO_SNOOP_OVERRIDE_EN,
 				pcie->parf + PARF_NO_SNOOP_OVERRIDE);
 
-	qcom_pcie_set_slot_nccs(pcie->pci);
+	qcom_pcie_set_slot_cap(pcie->pci);
 
 	return 0;
 }

---
base-commit: 3edb3a038d423480efeb204dbc6ddc9a292f8ecb
change-id: 20260710-clear_abp_0710-2f81e92b9da4

Best regards,
--  
Qiang Yu <qiang.yu@xxxxxxxxxxxxxxxx>