Hi Rob, On 1/26/22 6:40 PM, Robert Hancock wrote: > Hook up an optional GPIO-based reset for the connected USB ULPI PHY > device. This is typically already done by the first-stage boot loader, > however it can be more robust to ensure this reset is done prior to > loading the driver in Linux. > > Based on a patch "usb: dwc3: xilinx: Add gpio-reset support" in the > Xilinx kernel tree by Piyush Mehta <piyush.mehta@xxxxxxxxxx>. > > Signed-off-by: Robert Hancock <robert.hancock@xxxxxxxxxx> > --- > drivers/usb/dwc3/dwc3-xilinx.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c > index a6f3a9b38789..1ee6011ada44 100644 > --- a/drivers/usb/dwc3/dwc3-xilinx.c > +++ b/drivers/usb/dwc3/dwc3-xilinx.c > @@ -11,6 +11,7 @@ > #include <linux/slab.h> > #include <linux/clk.h> > #include <linux/of.h> > +#include <linux/gpio/consumer.h> > #include <linux/platform_device.h> > #include <linux/dma-mapping.h> > #include <linux/of_platform.h> > @@ -101,6 +102,7 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data) > struct phy *usb3_phy; > int ret = 0; > u32 reg; > + struct gpio_desc *reset_gpio; > > usb3_phy = devm_phy_optional_get(dev, "usb3-phy"); > if (IS_ERR(usb3_phy)) { > @@ -110,6 +112,14 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data) > goto err; > } > > + reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); > + if (IS_ERR(reset_gpio)) { > + ret = PTR_ERR(reset_gpio); > + dev_err_probe(dev, ret, > + "Failed to get reset gpio\n"); > + goto err; > + } > + > /* > * The following core resets are not required unless a USB3 PHY > * is used, and the subsequent register settings are not required > @@ -201,6 +211,15 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data) > } > > skip_usb3_phy: > + /* ulpi reset via gpio-modepin or gpio-framework driver */ > + if (reset_gpio) { > + /* Toggle ulpi to reset the phy. */ > + gpiod_set_value(reset_gpio, 0); > + usleep_range(5000, 10000); /* delay */ > + gpiod_set_value(reset_gpio, 1); > + usleep_range(5000, 10000); /* delay */ > + } > + > /* > * This routes the USB DMA traffic to go through FPD path instead > * of reaching DDR directly. This traffic routing is needed to > Do we need to have this in dwc3? Why not just use the usb-nop-xceiv driver (aka usb_phy_generic)? --Sean