> On Mon, Nov 04, 2024 at 11:00:05PM +0100, Lorenzo Bianconi wrote: > > 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 via the clock > > module. > > Introduce flags field in the mtk_gen3_pcie_pdata struct in order to > > specify per-SoC capabilities. > > Add blank lines between paragraphs so we know where they end. ack, I will fix it in v2. > > Where does this alternate way of doing reset (using REG_PCI_CONTROL > and REG_RESET_CONTROL) happen? Why isn't there something in this > patch to use that alternate method at the same points where > PCIE_PE_RSTB is used? REG_RESET_CONTROL (0x834) is already asserted/released in the following flow: mtk_pcie_en7581_power_up() -> reset_control_bulk_deassert() -> en7523_reset_update() https://github.com/torvalds/linux/blob/master/drivers/clk/clk-en7523.c#L470 REG_PCI_CONTROL (0x88) is already asserted/released in the following flow: mtk_pcie_en7581_power_up() -> clk_bulk_enable() -> en7581_pci_enable() https://github.com/torvalds/linux/blob/master/drivers/clk/clk-en7523.c#L385 > > If we don't need to assert reset for Airoha EN7581, why do we need to > do it for the other SoCs? I guess the other SoCs (mtk ones) do not have the same hw issue with PCIE_PE_RSTB (but I am not sure about it). Regards, Lorenzo > > > Tested-by: Hui Ma <hui.ma@xxxxxxxxxx> > > Signed-off-by: Lorenzo Bianconi <lorenzo@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 66ce4b5d309bb6d64618c70ac5e0a529e0910511..8e4704ff3509867fc0ff799e9fb99e71e46756cd 100644 > > --- a/drivers/pci/controller/pcie-mediatek-gen3.c > > +++ b/drivers/pci/controller/pcie-mediatek-gen3.c > > @@ -125,10 +125,18 @@ > > > > 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); > > @@ -136,6 +144,7 @@ struct mtk_gen3_pcie_pdata { > > const char *id[MAX_NUM_PHY_RESETS]; > > int num_resets; > > } phy_resets; > > + u32 flags; > > }; > > > > /** > > @@ -402,22 +411,33 @@ 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 REG_PCI_CONTROL (0x88) and > > + * REG_RESET_CONTROL (0x834) registers available via the clock module. > > */ > > - 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. > > Blank line between paragraphs. > > > + */ > > + 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, > > @@ -1160,10 +1180,12 @@ 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"); > > > > @@ -1214,6 +1236,7 @@ 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: 3102ce10f3111e4c3b8fb233dc93f29e220adaf7 > > change-id: 20240920-pcie-en7581-rst-fix-8161658c13c4 > > > > Best regards, > > -- > > Lorenzo Bianconi <lorenzo@xxxxxxxxxx> > >
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