On Tue, 2022-01-25 at 18:02 -0600, 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 | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c
> index e14ac15e24c3..0778236509bf 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;
> u32 reg;
> + struct gpio_desc *reset_gpio;
>
> usb3_phy = devm_phy_optional_get(dev, "usb3-phy");
> if (IS_ERR(usb3_phy)) {
> @@ -201,6 +203,22 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx
> *priv_data)
> }
>
> skip_usb3_phy:
> + /* ulpi reset via gpio-modepin or gpio-framework driver */
> + reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> + if (IS_ERR(reset_gpio)) {
> + dev_err_probe(dev, PTR_ERR(reset_gpio),
> + "Failed to bind reset gpio\n");
> + goto err;
>
Just noticed this forgets to set the error code to PTR_ERR(reset_gpio) and
breaks in the deferred probe case. Also, this should be done earlier to avoid
bailing out too late in that case. Will resubmit a new patchset with this fix
for the remaining two patches (first 2 in this series were already merged).
> + }
> +
> + 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
--
Robert Hancock
Senior Hardware Designer, Calian Advanced Technologies
www.calian.com
