Airoha EN7581 has a hw bug asserting/releasing PERST# signal causing occasional PCIe link down issues. In order to overcome the problem, PERST# signal is not asserted/released during device probe or suspend/resume phase and the PCIe block is reset using en7523_reset_assert() and en7581_pci_enable(). 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 v4: - fix typos and comments - Link to v3: https://lore.kernel.org/r/20241113-pcie-en7581-rst-fix-v3-1-23c5082335f7@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 | 59 ++++++++++++++++++++--------- 1 file changed, 41 insertions(+), 18 deletions(-) diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c index be52e3a123abd0d0086f9f1a603e3abaa18f319f..74dfef8ce9ec1bbc28c4a25cd1025f92ba3638a7 100644 --- a/drivers/pci/controller/pcie-mediatek-gen3.c +++ b/drivers/pci/controller/pcie-mediatek-gen3.c @@ -133,10 +133,18 @@ struct mtk_gen3_pcie; #define PCIE_CONF_LINK2_CTL_STS (PCIE_CFG_OFFSET_ADDR + 0xb0) #define PCIE_CONF_LINK2_LCR2_LINK_SPEED GENMASK(3, 0) +enum mtk_gen3_pcie_flags { + SKIP_PCIE_RSTB = BIT(0), /* Skip PERST# assertion during device + * probing or suspend/resume phase 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); @@ -144,6 +152,7 @@ struct mtk_gen3_pcie_pdata { const char *id[MAX_NUM_PHY_RESETS]; int num_resets; } phy_resets; + u32 flags; }; /** @@ -438,22 +447,33 @@ 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 using en7523_reset_assert() and + * en7581_pci_enable(). */ - 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 revision 6.0. + * + * 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, @@ -1231,10 +1251,12 @@ 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)) { + /* Assert 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"); @@ -1285,6 +1307,7 @@ 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: 40384c840ea1944d7c5a392e8975ed088ecf0b37 change-id: 20250108-pcie-en7581-rst-fix-7472285d2191 Best regards, -- Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
