linux-kernel - [PATCH] usb: dwc3: xilinx: Prevent spike in reset signal

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Message-ID: <20250314155706.31058-1-mike.looijmans@topic.nl>
Date: Fri, 14 Mar 2025 16:56:07 +0100
From: Mike Looijmans <mike.looijmans@...ic.nl>
To: linux-usb@...r.kernel.org
CC: Mike Looijmans <mike.looijmans@...ic.nl>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Michal Simek <michal.simek@....com>,
	Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] usb: dwc3: xilinx: Prevent spike in reset signal

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@...ic.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. */
-		gpiod_set_value_cansleep(reset_gpio, 1);
 		usleep_range(5000, 10000);
 		gpiod_set_value_cansleep(reset_gpio, 0);
 		usleep_range(5000, 10000);
-- 
2.43.0


Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


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