From cf18fce4ed5c87def7d95554bfc864951b793e4c Mon Sep 17 00:00:00 2001 From: Ben Dooks Date: Mon, 21 Feb 2022 21:03:46 +0000 Subject: PCI: fu740: Drop redundant '-gpios' from DT GPIO lookup The calls to devm_gpiod_get_optional() have the -gpios at the end of the name but the GPIO core code is already adding the suffix during the lookup. This means the PCIe driver is not finding the necessary reset or power lines to allow initialisation of the PCIe. Drop the redundant '-gpios' when we look up GPIOs from the DT. This bug has not been noticed because if U-Boot has setup the GPIO lines for the hardware when it does the PCIe initialisation (either by booting from PCIe or user command to access PCIe) then the PCIe will work in Linux. The U-Boot as supplied by SiFive does not by default initialise any PCIe component. Link: https://lore.kernel.org/r/20220221210347.1335004-1-ben.dooks@codethink.co.uk Signed-off-by: Ben Dooks Signed-off-by: Lorenzo Pieralisi Signed-off-by: Bjorn Helgaas --- drivers/pci/controller/dwc/pcie-fu740.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/pci/controller/dwc') diff --git a/drivers/pci/controller/dwc/pcie-fu740.c b/drivers/pci/controller/dwc/pcie-fu740.c index 00cde9a248b5..842b7202b96e 100644 --- a/drivers/pci/controller/dwc/pcie-fu740.c +++ b/drivers/pci/controller/dwc/pcie-fu740.c @@ -259,11 +259,11 @@ static int fu740_pcie_probe(struct platform_device *pdev) return PTR_ERR(afp->mgmt_base); /* Fetch GPIOs */ - afp->reset = devm_gpiod_get_optional(dev, "reset-gpios", GPIOD_OUT_LOW); + afp->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW); if (IS_ERR(afp->reset)) return dev_err_probe(dev, PTR_ERR(afp->reset), "unable to get reset-gpios\n"); - afp->pwren = devm_gpiod_get_optional(dev, "pwren-gpios", GPIOD_OUT_LOW); + afp->pwren = devm_gpiod_get_optional(dev, "pwren", GPIOD_OUT_LOW); if (IS_ERR(afp->pwren)) return dev_err_probe(dev, PTR_ERR(afp->pwren), "unable to get pwren-gpios\n"); -- cgit v1.2.3 From a382c757ec5ef83137a86125f43a4c43dc2ab50b Mon Sep 17 00:00:00 2001 From: Ben Dooks Date: Fri, 18 Mar 2022 15:24:30 +0000 Subject: PCI: fu740: Force 2.5GT/s for initial device probe The fu740 PCIe core does not probe any devices on the SiFive Unmatched board without this fix (or having U-Boot explicitly start the PCIe via either boot-script or user command). The fix is to start the link at 2.5GT/s speeds and once the link is up then change the maximum speed back to the default. The U-Boot driver claims to set the link-speed to 2.5GT/s to get the probe to work (and U-Boot does print link up at 2.5GT/s) in the following code: https://source.denx.de/u-boot/u-boot/-/blob/master/drivers/pci/pcie_dw_sifive.c?id=v2022.01#L271 Link: https://lore.kernel.org/r/20220318152430.526320-1-ben.dooks@codethink.co.uk Signed-off-by: Ben Dooks Signed-off-by: Bjorn Helgaas Acked-by: Palmer Dabbelt --- drivers/pci/controller/dwc/pcie-fu740.c | 51 ++++++++++++++++++++++++++++++++- 1 file changed, 50 insertions(+), 1 deletion(-) (limited to 'drivers/pci/controller/dwc') diff --git a/drivers/pci/controller/dwc/pcie-fu740.c b/drivers/pci/controller/dwc/pcie-fu740.c index 842b7202b96e..fd7b31729188 100644 --- a/drivers/pci/controller/dwc/pcie-fu740.c +++ b/drivers/pci/controller/dwc/pcie-fu740.c @@ -181,10 +181,59 @@ static int fu740_pcie_start_link(struct dw_pcie *pci) { struct device *dev = pci->dev; struct fu740_pcie *afp = dev_get_drvdata(dev); + u8 cap_exp = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP); + int ret; + u32 orig, tmp; + + /* + * Force 2.5GT/s when starting the link, due to some devices not + * probing at higher speeds. This happens with the PCIe switch + * on the Unmatched board when U-Boot has not initialised the PCIe. + * The fix in U-Boot is to force 2.5GT/s, which then gets cleared + * by the soft reset done by this driver. + */ + dev_dbg(dev, "cap_exp at %x\n", cap_exp); + dw_pcie_dbi_ro_wr_en(pci); + + tmp = dw_pcie_readl_dbi(pci, cap_exp + PCI_EXP_LNKCAP); + orig = tmp & PCI_EXP_LNKCAP_SLS; + tmp &= ~PCI_EXP_LNKCAP_SLS; + tmp |= PCI_EXP_LNKCAP_SLS_2_5GB; + dw_pcie_writel_dbi(pci, cap_exp + PCI_EXP_LNKCAP, tmp); /* Enable LTSSM */ writel_relaxed(0x1, afp->mgmt_base + PCIEX8MGMT_APP_LTSSM_ENABLE); - return 0; + + ret = dw_pcie_wait_for_link(pci); + if (ret) { + dev_err(dev, "error: link did not start\n"); + goto err; + } + + tmp = dw_pcie_readl_dbi(pci, cap_exp + PCI_EXP_LNKCAP); + if ((tmp & PCI_EXP_LNKCAP_SLS) != orig) { + dev_dbg(dev, "changing speed back to original\n"); + + tmp &= ~PCI_EXP_LNKCAP_SLS; + tmp |= orig; + dw_pcie_writel_dbi(pci, cap_exp + PCI_EXP_LNKCAP, tmp); + + tmp = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL); + tmp |= PORT_LOGIC_SPEED_CHANGE; + dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, tmp); + + ret = dw_pcie_wait_for_link(pci); + if (ret) { + dev_err(dev, "error: link did not start at new speed\n"); + goto err; + } + } + + ret = 0; +err: + WARN_ON(ret); /* we assume that errors will be very rare */ + dw_pcie_dbi_ro_wr_dis(pci); + return ret; } static int fu740_pcie_host_init(struct pcie_port *pp) -- cgit v1.2.3