From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> To: Trent Piepho <tpiepho@impinj.com> Cc: "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>, Richard Zhu <hongxing.zhu@nxp.com>, Shawn Guo <shawnguo@kernel.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, Lucas Stach <l.stach@pengutronix.de> Subject: Re: [PATCH v2 3/3] PCI: imx: Add workaround for e10728, IMX7d PCIe PLL failure Date: Thu, 7 Feb 2019 12:31:32 +0000 Message-ID: <20190207123132.GA21111@e107981-ln.cambridge.arm.com> (raw) In-Reply-To: <20190205001721.18639-4-tpiepho@impinj.com> On Tue, Feb 05, 2019 at 12:17:41AM +0000, Trent Piepho wrote: > This implements the workound described in the NXP IMX7d erratum e10728. > > Initial VCO oscillation may fail under corner conditions such as cold > temperature. It causes PCIe PLL to fail to lock in the initialization > phase, which results in the PCIe link failing to come up. > > The workaround is to disable Duty-cycle Corrector (DCC) calibration > after G_RST. > > To do this it is necessary to gain access to the undocumented and > currently unused PCIe PHY register bank. A new device tree node of type > "fsl,imx7d-pcie-phy" is created for the PHY block and the existing PCIe > device uses a phandle named "fsl,imx7d-pcie-phy" to point to it. > > Signed-off-by: Trent Piepho <tpiepho@impinj.com> > --- > drivers/pci/controller/dwc/pci-imx6.c | 57 +++++++++++++++++++++++++++++++++++ > 1 file changed, 57 insertions(+) > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c > index 80f843030e36..06dd6aa927d4 100644 > --- a/drivers/pci/controller/dwc/pci-imx6.c > +++ b/drivers/pci/controller/dwc/pci-imx6.c > @@ -18,6 +18,7 @@ > #include <linux/module.h> > #include <linux/of_gpio.h> > #include <linux/of_device.h> > +#include <linux/of_address.h> > #include <linux/pci.h> > #include <linux/platform_device.h> > #include <linux/regmap.h> > @@ -61,6 +62,7 @@ struct imx6_pcie { > u32 tx_swing_low; > int link_gen; > struct regulator *vpcie; > + void __iomem *phy_base; > > /* power domain for pcie */ > struct device *pd_pcie; > @@ -117,6 +119,23 @@ struct imx6_pcie { > #define PCIE_PHY_RX_ASIC_OUT 0x100D > #define PCIE_PHY_RX_ASIC_OUT_VALID (1 << 0) > > +/* iMX7 PCIe PHY registers */ > +#define PCIE_PHY_CMN_REG4 0x14 > +/* These are probably the bits that *aren't* DCC_FB_EN */ > +#define PCIE_PHY_CMN_REG4_DCC_FB_EN 0x29 > + > +#define PCIE_PHY_CMN_REG15 0x54 > +#define PCIE_PHY_CMN_REG15_DLY_4 BIT(2) > +#define PCIE_PHY_CMN_REG15_PLL_PD BIT(5) > +#define PCIE_PHY_CMN_REG15_OVRD_PLL_PD BIT(7) > + > +#define PCIE_PHY_CMN_REG24 0x90 > +#define PCIE_PHY_CMN_REG24_RX_EQ BIT(6) > +#define PCIE_PHY_CMN_REG24_RX_EQ_SEL BIT(3) > + > +#define PCIE_PHY_CMN_REG26 0x98 > +#define PCIE_PHY_CMN_REG26_ATT_MODE 0xBC > + > #define PHY_RX_OVRD_IN_LO 0x1005 > #define PHY_RX_OVRD_IN_LO_RX_DATA_EN (1 << 5) > #define PHY_RX_OVRD_IN_LO_RX_PLL_EN (1 << 3) > @@ -490,6 +509,26 @@ static void imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie) > switch (imx6_pcie->variant) { > case IMX7D: > reset_control_deassert(imx6_pcie->pciephy_reset); > + > + /* Workaround for ERR010728, failure of PCI-e PLL VCO to > + * oscillate, especially when cold. This turns off "Duty-cycle > + * Corrector" and other mysterious undocumented things. > + */ > + if (likely(imx6_pcie->phy_base)) { Nit: this is not a fast-path, so this branch performance is hardly relevant. > + /* De-assert DCC_FB_EN */ > + writel(PCIE_PHY_CMN_REG4_DCC_FB_EN, > + imx6_pcie->phy_base + PCIE_PHY_CMN_REG4); > + /* Assert RX_EQS and RX_EQS_SEL */ > + writel(PCIE_PHY_CMN_REG24_RX_EQ_SEL > + | PCIE_PHY_CMN_REG24_RX_EQ, > + imx6_pcie->phy_base + PCIE_PHY_CMN_REG24); > + /* Assert ATT_MODE */ > + writel(PCIE_PHY_CMN_REG26_ATT_MODE, > + imx6_pcie->phy_base + PCIE_PHY_CMN_REG26); > + } else { > + dev_warn(dev, "DT lacks imx7d-pcie-phy, unable to apply ERR010728 workaround\n"); It is a nit but the warning log is not necessarily true ie you may not have a mapped address for other reasons as well. It is up to you but I would change the log message. Thanks, Lorenzo > + } > + > imx7d_pcie_wait_for_phy_pll_lock(imx6_pcie); > break; > case IMX6SX: > @@ -919,6 +958,7 @@ static int imx6_pcie_probe(struct platform_device *pdev) > struct device *dev = &pdev->dev; > struct dw_pcie *pci; > struct imx6_pcie *imx6_pcie; > + struct device_node *np; > struct resource *dbi_base; > struct device_node *node = dev->of_node; > int ret; > @@ -939,6 +979,23 @@ static int imx6_pcie_probe(struct platform_device *pdev) > imx6_pcie->variant = > (enum imx6_pcie_variants)of_device_get_match_data(dev); > > + /* Find the PHY if one is defined, only imx7d uses it */ > + np = of_parse_phandle(node, "fsl,imx7d-pcie-phy", 0); > + if (np) { > + struct resource res; > + > + ret = of_address_to_resource(np, 0, &res); > + if (ret) { > + dev_err(dev, "Unable to map PCIe PHY\n"); > + return ret; > + } > + imx6_pcie->phy_base = devm_ioremap_resource(dev, &res); > + if (IS_ERR(imx6_pcie->phy_base)) { > + dev_err(dev, "Unable to map PCIe PHY\n"); > + return PTR_ERR(imx6_pcie->phy_base); > + } > + } > + > dbi_base = platform_get_resource(pdev, IORESOURCE_MEM, 0); > pci->dbi_base = devm_ioremap_resource(dev, dbi_base); > if (IS_ERR(pci->dbi_base)) > -- > 2.14.4 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply index Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-02-05 0:17 [PATCH v2 0/3] Workaround for IMX7d PCI-e PLL lock failure Trent Piepho 2019-02-05 0:17 ` [PATCH v2 1/3] dt-bindings: imx6q-pcie: Add description of imx7d pcie phy Trent Piepho 2019-02-05 9:43 ` Lucas Stach 2019-02-05 0:17 ` [PATCH v2 2/3] ARM: dts: imx7d: Add node for PCIe PHY Trent Piepho 2019-02-05 9:47 ` Lucas Stach 2019-02-05 0:17 ` [PATCH v2 3/3] PCI: imx: Add workaround for e10728, IMX7d PCIe PLL failure Trent Piepho 2019-02-05 9:48 ` Lucas Stach 2019-02-07 12:31 ` Lorenzo Pieralisi [this message] 2019-02-07 18:15 ` Trent Piepho 2019-02-08 10:18 ` Lorenzo Pieralisi 2019-02-08 18:19 ` Trent Piepho 2019-02-11 12:18 ` Lorenzo Pieralisi
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