Airoha EN7581 has a hw bug asserting/releasing PCIE_PE_RSTB signal causing occasional PCIe link down issues. In order to overcome the problem, PCIE_RSTB signals are not asserted/released during device probe or suspend/resume phase and the PCIe block is reset using REG_PCI_CONTROL (0x88) and REG_RESET_CONTROL (0x834) registers available in the clock module running clk_bulk_prepare_enable in mtk_pcie_en7581_power_up(). Introduce flags field in the mtk_gen3_pcie_pdata struct in order to specify per-SoC capabilities. Tested-by: Hui Ma <hui.ma@xxxxxxxxxx> Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx> --- Changes in v3: - cosmetics - Link to v2: https://lore.kernel.org/r/20241104-pcie-en7581-rst-fix-v2-1-ffe5839c76d8@xxxxxxxxxx Changes in v2: - introduce flags field in mtk_gen3_pcie_flags struct instead of adding reset callback - fix the leftover case in mtk_pcie_suspend_noirq routine - add more comments - Link to v1: https://lore.kernel.org/r/20240920-pcie-en7581-rst-fix-v1-1-1043fb63ffc9@xxxxxxxxxx --- drivers/pci/controller/pcie-mediatek-gen3.c | 60 ++++++++++++++++++++--------- 1 file changed, 42 insertions(+), 18 deletions(-) diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c index 16a55711a7f3bdc8d6620029e3d2cfdd40b537b7..443072adb9b52a6934a5d1e38eb6fca5f86a1e13 100644 --- a/drivers/pci/controller/pcie-mediatek-gen3.c +++ b/drivers/pci/controller/pcie-mediatek-gen3.c @@ -128,10 +128,18 @@ struct mtk_gen3_pcie; +enum mtk_gen3_pcie_flags { + SKIP_PCIE_RSTB = BIT(0), /* skip PCIE_RSTB signals configuration + * during device probing or suspend/resume + * phase in order to avoid hw bugs/issues. + */ +}; + /** * struct mtk_gen3_pcie_pdata - differentiate between host generations * @power_up: pcie power_up callback * @phy_resets: phy reset lines SoC data. + * @flags: pcie device flags. */ struct mtk_gen3_pcie_pdata { int (*power_up)(struct mtk_gen3_pcie *pcie); @@ -139,6 +147,7 @@ struct mtk_gen3_pcie_pdata { const char *id[MAX_NUM_PHY_RESETS]; int num_resets; } phy_resets; + u32 flags; }; /** @@ -405,22 +414,34 @@ static int mtk_pcie_startup_port(struct mtk_gen3_pcie *pcie) val |= PCIE_DISABLE_DVFSRC_VLT_REQ; writel_relaxed(val, pcie->base + PCIE_MISC_CTRL_REG); - /* Assert all reset signals */ - val = readl_relaxed(pcie->base + PCIE_RST_CTRL_REG); - val |= PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB | PCIE_PE_RSTB; - writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG); - /* - * Described in PCIe CEM specification sections 2.2 (PERST# Signal) - * and 2.2.1 (Initial Power-Up (G3 to S0)). - * The deassertion of PERST# should be delayed 100ms (TPVPERL) - * for the power and clock to become stable. + * Airoha EN7581 has a hw bug asserting/releasing PCIE_PE_RSTB signal + * causing occasional PCIe link down. In order to overcome the issue, + * PCIE_RSTB signals are not asserted/released at this stage and the + * PCIe block is reset configuting REG_PCI_CONTROL (0x88) and + * REG_RESET_CONTROL (0x834) registers available in the clock module + * running clk_bulk_prepare_enable in mtk_pcie_en7581_power_up(). */ - msleep(100); - - /* De-assert reset signals */ - val &= ~(PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB | PCIE_PE_RSTB); - writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG); + if (!(pcie->soc->flags & SKIP_PCIE_RSTB)) { + /* Assert all reset signals */ + val = readl_relaxed(pcie->base + PCIE_RST_CTRL_REG); + val |= PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB | + PCIE_PE_RSTB; + writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG); + + /* + * Described in PCIe CEM specification sections 2.2 (PERST# Signal) + * and 2.2.1 (Initial Power-Up (G3 to S0)). + * The deassertion of PERST# should be delayed 100ms (TPVPERL) + * for the power and clock to become stable. + */ + msleep(PCIE_T_PVPERL_MS); + + /* De-assert reset signals */ + val &= ~(PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB | + PCIE_PE_RSTB); + writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG); + } /* Check if the link is up or not */ err = readl_poll_timeout(pcie->base + PCIE_LINK_STATUS_REG, val, @@ -1179,10 +1200,12 @@ static int mtk_pcie_suspend_noirq(struct device *dev) return err; } - /* Pull down the PERST# pin */ - val = readl_relaxed(pcie->base + PCIE_RST_CTRL_REG); - val |= PCIE_PE_RSTB; - writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG); + if (!(pcie->soc->flags & SKIP_PCIE_RSTB)) { + /* Pull down the PERST# pin */ + val = readl_relaxed(pcie->base + PCIE_RST_CTRL_REG); + val |= PCIE_PE_RSTB; + writel_relaxed(val, pcie->base + PCIE_RST_CTRL_REG); + } dev_dbg(pcie->dev, "entered L2 states successfully"); @@ -1233,6 +1256,7 @@ static const struct mtk_gen3_pcie_pdata mtk_pcie_soc_en7581 = { .id[2] = "phy-lane2", .num_resets = 3, }, + .flags = SKIP_PCIE_RSTB, }; static const struct of_device_id mtk_pcie_of_match[] = { --- base-commit: ff80d707f3cb5e8d9ec0739e0e5ed42dea179125 change-id: 20240920-pcie-en7581-rst-fix-8161658c13c4 Best regards, -- Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
