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
