linux-kernel - [PATCH] usb: dwc3: don't reset device side if dwc3 was configured as host-only

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Date:   Wed, 28 Jun 2023 00:20:18 +0800
From:   Jisheng Zhang <jszhang@...nel.org>
To:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] usb: dwc3: don't reset device side if dwc3 was configured as host-only

Commit c4a5153e87fd ("usb: dwc3: core: Power-off core/PHYs on
system_suspend in host mode") replaces check for HOST only dr_mode with
current_dr_role. But during booting, the current_dr_role isn't
initialized, thus the device side reset is always issued even if dwc3
was configured as host-only. What's more, on some platforms with host
only dwc3, aways issuing device side reset by accessing device register
block can cause kernel panic.

Fixes: c4a5153e87fd ("usb: dwc3: core: Power-off core/PHYs on system_suspend in host mode")
Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
---
 drivers/usb/dwc3/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 7b2ce013cc5b..16d7a1d1cbfa 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -277,9 +277,9 @@ int dwc3_core_soft_reset(struct dwc3 *dwc)
 	/*
 	 * We're resetting only the device side because, if we're in host mode,
 	 * XHCI driver will reset the host block. If dwc3 was configured for
-	 * host-only mode, then we can return early.
+	 * host-only mode or current role is host, then we can return early.
 	 */
-	if (dwc->current_dr_role == DWC3_GCTL_PRTCAP_HOST)
+	if (dwc->dr_mode == USB_DR_MODE_HOST || dwc->current_dr_role == DWC3_GCTL_PRTCAP_HOST)
 		return 0;
 
 	reg = dwc3_readl(dwc->regs, DWC3_DCTL);
-- 
2.40.1