> On Tue, 2024-11-05 at 10:30 +0100, lorenzo@xxxxxxxxxx wrote: > > > On Mon, 2024-11-04 at 23:00 +0100, Lorenzo Bianconi wrote: > > > > External email : Please do not click links or open attachments > > > > until > > > > you have verified the sender or the content. > > > > > > > > > > > > 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. > > > > > > > > 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..8e4704ff3509867fc0ff799 > > > > e9fb > > > > 99e71e46756cd 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); > > > > > > What will happen if the EN7581 use this reset flow? Will it still > > > work > > > after this link down? > > > > Hi Jianjun Wang, > > > > This has been described here by Hui Ma: > > > https://lore.kernel.org/r/20240920-pcie-en7581-rst-fix-v1-1-1043fb63ffc9@xxxxxxxxxx > > > > Setting PCIE_PE_RSTB bit on EN7581 SoC during reset triggers > > occasional PCIe link > > down issues caused by a hw problem. > > Hi Lorenzo, > > I'm wondering if we can ignore the previous reset and take this one as > the initial reset? Hi Jianjun Wang, according to my understanding from Hui Ma's description, EN7581 has a hw issue with PCIE_PE_RSTB and it can't rely on it. Regards, Lorenzo > > Thanks. > > > > > Regards, > > Lorenzo > > > > > > > > > + 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, > > > > @@ -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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