| Message ID | 20250314155706.31058-1-mike.looijmans@topic.nl (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | usb: dwc3: xilinx: Prevent spike in reset signal | expand |
On Fri, Mar 14, 2025, Mike Looijmans wrote: > Set the gpio to "high" on acquisition, instead of acquiring it in low > state and then immediately setting it high again. This prevents a > short "spike" on the reset signal. How does this affect the current programming flow beside preventing a spike to the reset signal? > > Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl> > --- > > drivers/usb/dwc3/dwc3-xilinx.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c > index a33a42ba0249..a159a511483b 100644 > --- a/drivers/usb/dwc3/dwc3-xilinx.c > +++ b/drivers/usb/dwc3/dwc3-xilinx.c > @@ -207,7 +207,7 @@ 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_LOW); > + reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); > if (IS_ERR(reset_gpio)) { > return dev_err_probe(dev, PTR_ERR(reset_gpio), > "Failed to request reset GPIO\n"); > @@ -215,7 +215,6 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data) > > if (reset_gpio) { > /* Toggle ulpi to reset the phy. */ Does the comment above still apply? > - gpiod_set_value_cansleep(reset_gpio, 1); > usleep_range(5000, 10000); Do we still need this usleep_range here? BR, Thinh > gpiod_set_value_cansleep(reset_gpio, 0); > usleep_range(5000, 10000); > -- > 2.43.0 > > > Met vriendelijke groet / kind regards, > > Mike Looijmans > System Expert > > > TOPIC Embedded Products B.V. > Materiaalweg 4, 5681 RJ Best > The Netherlands > > T: +31 (0) 499 33 69 69 > E: mike.looijmans@topic.nl > W: https://urldefense.com/v3/__http://www.topic.nl__;!!A4F2R9G_pg!dt2SxHPWske2gY2PNQ9GrJEr5lXXkUCMb5CMBd2ymPEYpU1TEemM__y9_6QwiMTyCIX9wXKKAOzhX5Ex5x5FWa1QV5I98u0$ > > Please consider the environment before printing this e-mail
diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c index a33a42ba0249..a159a511483b 100644 --- a/drivers/usb/dwc3/dwc3-xilinx.c +++ b/drivers/usb/dwc3/dwc3-xilinx.c @@ -207,7 +207,7 @@ 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_LOW); + reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); if (IS_ERR(reset_gpio)) { return dev_err_probe(dev, PTR_ERR(reset_gpio), "Failed to request reset GPIO\n"); @@ -215,7 +215,6 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data) if (reset_gpio) { /* Toggle ulpi to reset the phy. */ - gpiod_set_value_cansleep(reset_gpio, 1); usleep_range(5000, 10000); gpiod_set_value_cansleep(reset_gpio, 0); usleep_range(5000, 10000);
Set the gpio to "high" on acquisition, instead of acquiring it in low state and then immediately setting it high again. This prevents a short "spike" on the reset signal. Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl> --- drivers/usb/dwc3/dwc3-xilinx.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)