linux-kernel - [PATCH] usb: dwc3: fix fault at system suspend if device was already runtime suspended

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Message-Id: <20241104-am62-lpm-usb-fix-v1-1-e93df73a4f0d@kernel.org>
Date: Mon, 04 Nov 2024 16:00:11 +0200
From: Roger Quadros <rogerq@...nel.org>
To: Thinh Nguyen <Thinh.Nguyen@...opsys.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Dhruva Gole <d-gole@...com>, sashal@...nel.org, 
 William McVicker <willmcvicker@...gle.com>, 
 Chris Morgan <macroalpha82@...il.com>
Cc: Vishal Mahaveer <vishalm@...com>, msp@...libre.com, srk@...com, 
 linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, 
 stable@...r.kernel.org, Roger Quadros <rogerq@...nel.org>
Subject: [PATCH] usb: dwc3: fix fault at system suspend if device was
 already runtime suspended

If the device was already runtime suspended then during system suspend
we cannot access the device registers else it will crash.

Also we cannot access any registers after dwc3_core_exit() on some
platforms so move the dwc3_enable_susphy() call to the top.

Cc: stable@...r.kernel.org # v5.15+
Reported-by: William McVicker <willmcvicker@...gle.com>
Closes: https://lore.kernel.org/all/ZyVfcUuPq56R2m1Y@google.com
Fixes: 705e3ce37bcc ("usb: dwc3: core: Fix system suspend on TI AM62 platforms")
Signed-off-by: Roger Quadros <rogerq@...nel.org>
---
 drivers/usb/dwc3/core.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 427e5660f87c..98114c2827c0 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -2342,10 +2342,18 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 	u32 reg;
 	int i;
 
-	dwc->susphy_state = (dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0)) &
-			    DWC3_GUSB2PHYCFG_SUSPHY) ||
-			    (dwc3_readl(dwc->regs, DWC3_GUSB3PIPECTL(0)) &
-			    DWC3_GUSB3PIPECTL_SUSPHY);
+	if (!pm_runtime_suspended(dwc->dev) && !PMSG_IS_AUTO(msg)) {
+		dwc->susphy_state = (dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0)) &
+				    DWC3_GUSB2PHYCFG_SUSPHY) ||
+				    (dwc3_readl(dwc->regs, DWC3_GUSB3PIPECTL(0)) &
+				    DWC3_GUSB3PIPECTL_SUSPHY);
+		/*
+		 * TI AM62 platform requires SUSPHY to be
+		 * enabled for system suspend to work.
+		 */
+		if (!dwc->susphy_state)
+			dwc3_enable_susphy(dwc, true);
+	}
 
 	switch (dwc->current_dr_role) {
 	case DWC3_GCTL_PRTCAP_DEVICE:
@@ -2398,15 +2406,6 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
 		break;
 	}
 
-	if (!PMSG_IS_AUTO(msg)) {
-		/*
-		 * TI AM62 platform requires SUSPHY to be
-		 * enabled for system suspend to work.
-		 */
-		if (!dwc->susphy_state)
-			dwc3_enable_susphy(dwc, true);
-	}
-
 	return 0;
 }
 

---
base-commit: 42f7652d3eb527d03665b09edac47f85fb600924
change-id: 20241102-am62-lpm-usb-fix-347dd86135c1

Best regards,
-- 
Roger Quadros <rogerq@...nel.org>