[PATCH v2 3/5] PCI: qcom: Add .get_ltssm() helper
From: Krishna Chaitanya Chundru <hidden>
Date: 2026-02-17 11:19:28
Also in:
linux-arm-msm, linux-pci, lkml
Subsystem:
arm/qualcomm mailing list, pci native host bridge and endpoint drivers, pci subsystem, pcie driver for qualcomm msm, the rest · Maintainers:
Lorenzo Pieralisi, Krzysztof Wilczyński, Manivannan Sadhasivam, Bjorn Helgaas, Linus Torvalds
For older targets like sc7280, we see reading DBI after sending PME turn off message is causing NOC error. To avoid unsafe DBI accesses, introduce qcom_pcie_get_ltssm(), which retrieves the LTSSM state from the PARF_LTSSM register instead. Signed-off-by: Krishna Chaitanya Chundru <redacted> --- drivers/pci/controller/dwc/pcie-qcom.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 67a16af69ddc75fca1b123e70715e692a91a9135..2c4dc7134e006d3530a809f1bcc1a6488d4632ad 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c@@ -131,6 +131,7 @@ /* PARF_LTSSM register fields */ #define LTSSM_EN BIT(8) +#define PARF_LTSSM_STATE_MASK GENMASK(5, 0) /* PARF_NO_SNOOP_OVERRIDE register fields */ #define WR_NO_SNOOP_OVERRIDE_EN BIT(1)
@@ -1255,6 +1256,15 @@ static bool qcom_pcie_link_up(struct dw_pcie *pci) return val & PCI_EXP_LNKSTA_DLLLA; } +static enum dw_pcie_ltssm qcom_pcie_get_ltssm(struct dw_pcie *pci) +{ + struct qcom_pcie *pcie = to_qcom_pcie(pci); + u32 val; + + val = readl(pcie->parf + PARF_LTSSM); + return (enum dw_pcie_ltssm)FIELD_GET(PARF_LTSSM_STATE_MASK, val); +} + static void qcom_pcie_phy_power_off(struct qcom_pcie *pcie) { struct qcom_pcie_port *port;
@@ -1507,6 +1517,7 @@ static const struct qcom_pcie_cfg cfg_fw_managed = { static const struct dw_pcie_ops dw_pcie_ops = { .link_up = qcom_pcie_link_up, .start_link = qcom_pcie_start_link, + .get_ltssm = qcom_pcie_get_ltssm, }; static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
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2.34.1