linux-kernel - [PATCH] usb: dwc3: Fix timeout issue during controller enter/exit from halt state

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Message-ID: <20250131110832.438-1-selvarasu.g@samsung.com>
Date: Fri, 31 Jan 2025 16:38:30 +0530
From: Selvarasu Ganesan <selvarasu.g@...sung.com>
To: Thinh.Nguyen@...opsys.com, gregkh@...uxfoundation.org, balbi@...com,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: jh0801.jung@...sung.com, dh10.jung@...sung.com, naushad@...sung.com,
	akash.m5@...sung.com, h10.kim@...sung.com, eomji.oh@...sung.com,
	alim.akhtar@...sung.com, thiagu.r@...sung.com, Selvarasu Ganesan
	<selvarasu.g@...sung.com>, stable@...r.kernel.org
Subject: [PATCH] usb: dwc3: Fix timeout issue during controller enter/exit
 from halt state

There is a frequent timeout during controller enter/exit from halt state
after toggling the run_stop bit by SW. This timeout occurs when
performing frequent role switches between host and device, causing
device enumeration issues due to the timeout. This issue was not present
when USB2 suspend PHY was disabled by passing the SNPS quirks
(snps,dis_u2_susphy_quirk and snps,dis_enblslpm_quirk) from the DTS.
However, there is a requirement to enable USB2 suspend PHY by setting of
GUSB2PHYCFG.ENBLSLPM and GUSB2PHYCFG.SUSPHY bits when controller starts
in gadget or host mode results in the timeout issue.

This commit addresses this timeout issue by ensuring that the bits
GUSB2PHYCFG.ENBLSLPM and GUSB2PHYCFG.SUSPHY are cleared before starting
the dwc3_gadget_run_stop sequence and restoring them after the
dwc3_gadget_run_stop sequence is completed.

Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
Cc: stable@...r.kernel.org
Signed-off-by: Selvarasu Ganesan <selvarasu.g@...sung.com>
---
 drivers/usb/dwc3/gadget.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index d27af65eb08a..4a158f703d64 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2629,10 +2629,25 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on)
 {
 	u32			reg;
 	u32			timeout = 2000;
+	u32			saved_config = 0;
 
 	if (pm_runtime_suspended(dwc->dev))
 		return 0;
 
+	reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
+	if (unlikely(reg & DWC3_GUSB2PHYCFG_SUSPHY)) {
+		saved_config |= DWC3_GUSB2PHYCFG_SUSPHY;
+		reg &= ~DWC3_GUSB2PHYCFG_SUSPHY;
+	}
+
+	if (reg & DWC3_GUSB2PHYCFG_ENBLSLPM) {
+		saved_config |= DWC3_GUSB2PHYCFG_ENBLSLPM;
+		reg &= ~DWC3_GUSB2PHYCFG_ENBLSLPM;
+	}
+
+	if (saved_config)
+		dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
+
 	reg = dwc3_readl(dwc->regs, DWC3_DCTL);
 	if (is_on) {
 		if (DWC3_VER_IS_WITHIN(DWC3, ANY, 187A)) {
@@ -2660,6 +2675,12 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on)
 		reg &= DWC3_DSTS_DEVCTRLHLT;
 	} while (--timeout && !(!is_on ^ !reg));
 
+	if (saved_config) {
+		reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
+		reg |= saved_config;
+		dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
+	}
+
 	if (!timeout)
 		return -ETIMEDOUT;
 
-- 
2.17.1