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Merge branch 'pci/host/fu740'

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- Drop redundant '-gpios' from DT GPIO lookup (Ben Dooks)

- Force 2.5GT/s for initial device probe to workaround enumeration issue on
  SiFive Unmatched board (Ben Dooks)

* pci/host/fu740:
  PCI: fu740: Force 2.5GT/s for initial device probe
  PCI: fu740: Drop redundant '-gpios' from DT GPIO lookup
This commit is contained in:
Bjorn Helgaas 2022-03-22 17:16:24 -05:00
commit d93fefad20
1 changed files with 52 additions and 3 deletions
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55
drivers/pci/controller/dwc/pcie-fu740.c
View file

@ -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)
@ -259,11 +308,11 @@ 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");