linux-kernel - [PATCH v2 5/8] PCI: qcom: Do not advertise hotplug capability for IP v2.3.2

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Date:   Fri, 19 May 2023 20:01:14 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     lpieralisi@...nel.org, kw@...ux.com, bhelgaas@...gle.com
Cc:     robh@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, steev@...i.org,
        quic_srichara@...cinc.com, dmitry.baryshkov@...aro.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH v2 5/8] PCI: qcom: Do not advertise hotplug capability for IP v2.3.2

SoCs making use of Qcom PCIe controller IP v2.3.2 do not support hotplug
functionality. But the hotplug capability bit is set by default in the
hardware. This causes the kernel PCI core to register hotplug service for
the controller and send hotplug commands to it. But those commands will
timeout generating messages as below during boot and suspend/resume.

[    5.782159] pcieport 0001:00:00.0: pciehp: Timeout on hotplug command 0x03c0 (issued 2020 msec ago)
[    5.810161] pcieport 0001:00:00.0: pciehp: Timeout on hotplug command 0x03c0 (issued 2048 msec ago)
[    7.838162] pcieport 0001:00:00.0: pciehp: Timeout on hotplug command 0x07c0 (issued 2020 msec ago)
[    7.870159] pcieport 0001:00:00.0: pciehp: Timeout on hotplug command 0x07c0 (issued 2052 msec ago)

This not only spams the console output but also induces a delay of a
couple of seconds. To fix this issue, let's clear the HPC bit in
PCI_EXP_SLTCAP register as a part of the post init sequence to not
advertise the hotplug capability for the controller.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 64b6a8c6a99d..9c8dfd224e6e 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -616,6 +616,8 @@ 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_clear_hpc(pcie->pci);
+
 	return 0;
 }
 
-- 
2.25.1