linux-kernel - [PATCH] usb: dwc2: also exit clock_gating when stopping udc while suspended

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Message-Id: <20250417-dwc2_clock_gating-v1-1-8ea7c4d53d73@pengutronix.de>
Date: Thu, 17 Apr 2025 19:40:17 +0200
From: Michael Grzeschik <m.grzeschik@...gutronix.de>
To: Minas Harutyunyan <hminas@...opsys.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, 
 kernel@...gutronix.de, Michael Grzeschik <m.grzeschik@...gutronix.de>
Subject: [PATCH] usb: dwc2: also exit clock_gating when stopping udc while
 suspended

It is possible that the gadget will be disabled, while the udc is
suspended. When enabling the udc in that case, the clock gating
will not be enabled again. Leaving the phy unclocked. Even when the
udc is not enabled, connecting this powered but not clocked phy leads
to enumeration errors on the host side.

To ensure that the clock gating will be in an valid state, we ensure
that the clock gating will be enabled before stopping the udc.

Signed-off-by: Michael Grzeschik <m.grzeschik@...gutronix.de>
---
 drivers/usb/dwc2/gadget.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index 300ea4969f0cf..f323fb5597b32 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -4604,6 +4604,12 @@ static int dwc2_hsotg_udc_stop(struct usb_gadget *gadget)
 	if (!hsotg)
 		return -ENODEV;
 
+	/* Exit clock gating when driver is stopped. */
+	if (hsotg->params.power_down == DWC2_POWER_DOWN_PARAM_NONE &&
+	    hsotg->bus_suspended && !hsotg->params.no_clock_gating) {
+		dwc2_gadget_exit_clock_gating(hsotg, 0);
+	}
+
 	/* all endpoints should be shutdown */
 	for (ep = 1; ep < hsotg->num_of_eps; ep++) {
 		if (hsotg->eps_in[ep])

---
base-commit: cfb2e2c57aef75a414c0f18445c7441df5bc13be
change-id: 20250417-dwc2_clock_gating-579a87fcdf93

Best regards,
-- 
Michael Grzeschik <m.grzeschik@...gutronix.de>