On Thu, May 16, 2019 at 11:23:06AM +0530, Manikanta Maddireddy wrote: > Add support for GPIO based PERST# signal. GPIO number comes from per port > PCIe device tree node. > > Signed-off-by: Manikanta Maddireddy > --- > V4: Using devm_gpiod_get_from_of_node() to get reset-gpios > > V3: Using helper function to get reset-gpios > > V2: Using standard "reset-gpio" property > > drivers/pci/controller/pci-tegra.c | 41 +++++++++++++++++++++++++----- > 1 file changed, 35 insertions(+), 6 deletions(-) > > diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c > index 06b99fcbf382..09b4d384ba38 100644 > --- a/drivers/pci/controller/pci-tegra.c > +++ b/drivers/pci/controller/pci-tegra.c > @@ -17,6 +17,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -400,6 +401,8 @@ struct tegra_pcie_port { > unsigned int lanes; > > struct phy **phys; > + > + struct gpio_desc *reset_gpiod; Nit: I'd leave away the "d" at the end there. Or perhaps even the _gpio suffix entirely. But it's fine either way. > }; > > struct tegra_pcie_bus { > @@ -583,15 +586,23 @@ static void tegra_pcie_port_reset(struct tegra_pcie_port *port) > unsigned long value; > > /* pulse reset signal */ > - value = afi_readl(port->pcie, ctrl); > - value &= ~AFI_PEX_CTRL_RST; > - afi_writel(port->pcie, value, ctrl); > + if (port->reset_gpiod) { > + gpiod_set_value(port->reset_gpiod, 0); So is this actually deasserting the reset pin, or is it asserting a low-active reset? I think it's the latter, because ... > + } else { > + value = afi_readl(port->pcie, ctrl); > + value &= ~AFI_PEX_CTRL_RST; > + afi_writel(port->pcie, value, ctrl); > + } > > usleep_range(1000, 2000); > > - value = afi_readl(port->pcie, ctrl); > - value |= AFI_PEX_CTRL_RST; > - afi_writel(port->pcie, value, ctrl); > + if (port->reset_gpiod) { > + gpiod_set_value(port->reset_gpiod, 1); After this the port should be functional, right? I think it'd be better to reverse the logic here and move the polarity of the GPIO into device tree. gpiod_set_value() takes care of inverting the level internally if the GPIO is marked as low-active in DT. The end result is obviously the same, but it makes the usage much clearer. If somebody want to write a DT for their board, they will look at the schematics and see a low-active reset line and may be tempted to describe it as such in DT, but with your current code that would be exactly the wrong way around. > + } else { > + value = afi_readl(port->pcie, ctrl); > + value |= AFI_PEX_CTRL_RST; > + afi_writel(port->pcie, value, ctrl); > + } > } > > static void tegra_pcie_enable_rp_features(struct tegra_pcie_port *port) > @@ -2238,6 +2249,7 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *pcie) > struct tegra_pcie_port *rp; > unsigned int index; > u32 value; > + char *label; > > err = of_pci_get_devfn(port); > if (err < 0) { > @@ -2296,6 +2308,23 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *pcie) > if (IS_ERR(rp->base)) > return PTR_ERR(rp->base); > > + label = kasprintf(GFP_KERNEL, "pex-reset-%u", index); devm_kasprintf()? Thierry > + if (!label) { > + dev_err(dev, "failed to create reset GPIO label\n"); > + return -ENOMEM; > + } > + > + rp->reset_gpiod = devm_gpiod_get_from_of_node(dev, port, > + "reset-gpios", 0, > + GPIOD_OUT_LOW, > + label); > + kfree(label); > + if (IS_ERR(rp->reset_gpiod)) { > + err = PTR_ERR(rp->reset_gpiod); > + dev_err(dev, "failed to get reset GPIO: %d\n", err); > + return err; > + } > + > list_add_tail(&rp->list, &pcie->ports); > } > > -- > 2.17.1 >