linux-kernel - [PATCH v2, 3/3] usb: dwc3: core: Workaround for CSR read timeout

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Message-Id: <20240603130219.25825-1-joswang1221@gmail.com>
Date: Mon,  3 Jun 2024 21:02:19 +0800
From: joswang <joswang1221@...il.com>
To: Thinh.Nguyen@...opsys.com,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org
Cc: gregkh@...uxfoundation.org,
	linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	balbi@...nel.org,
	devicetree@...r.kernel.org,
	joswang <joswang@...ovo.com>
Subject: [PATCH v2, 3/3] usb: dwc3: core: Workaround for CSR read timeout

From: joswang <joswang@...ovo.com>

DWC31 version 2.00a have an issue that would cause
a CSR read timeout When CSR read coincides with RAM
Clock Gating Entry.

This workaround solution disable Clock Gating, sacrificing
power consumption for normal operation.

Signed-off-by: joswang <joswang@...ovo.com>
---
 drivers/usb/dwc3/core.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 3a8fbc2d6b99..1df85c505c9e 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -978,11 +978,22 @@ static void dwc3_core_setup_global_control(struct dwc3 *dwc)
 		 *
 		 * STAR#9000588375: Clock Gating, SOF Issues when ref_clk-Based
 		 * SOF/ITP Mode Used
+		 *
+		 * WORKAROUND: DWC31 version 2.00a have an issue that would
+		 * cause a CSR read timeout When CSR read coincides with RAM
+		 * Clock Gating Entry.
+		 *
+		 * This workaround solution disable Clock Gating, sacrificing
+		 * power consumption for normal operation.
 		 */
 		if ((dwc->dr_mode == USB_DR_MODE_HOST ||
 				dwc->dr_mode == USB_DR_MODE_OTG) &&
 				DWC3_VER_IS_WITHIN(DWC3, 210A, 250A))
 			reg |= DWC3_GCTL_DSBLCLKGTNG | DWC3_GCTL_SOFITPSYNC;
+		else if ((dwc->dr_mode == USB_DR_MODE_HOST ||
+				dwc->dr_mode == USB_DR_MODE_OTG) &&
+				DWC3_VER_IS(DWC31, 200A))
+			reg |= DWC3_GCTL_DSBLCLKGTNG;
 		else
 			reg &= ~DWC3_GCTL_DSBLCLKGTNG;
 		break;
@@ -992,6 +1003,18 @@ static void dwc3_core_setup_global_control(struct dwc3 *dwc)
 		 * will work. Device-mode hibernation is not yet implemented.
 		 */
 		reg |= DWC3_GCTL_GBLHIBERNATIONEN;
+
+		/*
+		 * WORKAROUND: DWC31 version 2.00a have an issue that would
+		 * cause a CSR read timeout When CSR read coincides with RAM
+		 * Clock Gating Entry.
+		 *
+		 * This workaround solution disable Clock Gating, sacrificing
+		 * power consumption for normal operation.
+		 */
+		if ((dwc->dr_mode == USB_DR_MODE_HOST ||
+		     dwc->dr_mode == USB_DR_MODE_OTG) && DWC3_VER_IS(DWC31, 200A))
+			reg |= DWC3_GCTL_DSBLCLKGTNG;
 		break;
 	default:
 		/* nothing */
-- 
2.17.1