[PATCH v2 2/2] 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.

Reviewed-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
Tested-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx> # X1E80100 CRD
Signed-off-by: Qiang Yu <qiang.yu@xxxxxxxxxxxxxxxx>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 465c940109a7..0a826ba63277 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -372,6 +372,12 @@ static void qcom_pcie_set_slot_cap(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);

-- 
2.34.1