linux-kernel - [PATCH v2] usb: cdnsp: fix L1 resume issue for RTL_REVISION_NEW

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Message-ID:
 <PH7PR07MB9538B55C3A6E71F9ED29E980DD842@PH7PR07MB9538.namprd07.prod.outlook.com>
Date: Fri, 25 Apr 2025 05:55:40 +0000
From: Pawel Laszczak <pawell@...ence.com>
To: "peter.chen@...nel.org" <peter.chen@...nel.org>
CC: "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Pawel Laszczak
	<pawell@...ence.com>
Subject: [PATCH v2] usb: cdnsp: fix L1 resume issue for RTL_REVISION_NEW_LPM
 version

The controllers with rtl version larger than
RTL_REVISION_NEW_LPM (0x00002700) has bug which causes that controller
doesn't resume from L1 state. It happens if after receiving LPM packet
controller starts transitioning to L1 and in this moment the driver force
resuming by write operation to PORTSC.PLS.
It's corner case and happens when write operation to PORTSC occurs during
device delay before transitioning to L1 after transmitting ACK
time (TL1TokenRetry).

Forcing transition from L1->L0 by driver for revision larger than
RTL_REVISION_NEW_LPM is not needed, so driver can simply fix this issue
through block call of cdnsp_force_l0_go function.

Fixes: 3d82904559f4 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
cc: stable@...r.kernel.org
Signed-off-by: Pawel Laszczak <pawell@...ence.com>
---
Changelog:
v2:
- improved patch description
- changed RTL_REVISION_NEW_LPM value

 drivers/usb/cdns3/cdnsp-gadget.c | 2 ++
 drivers/usb/cdns3/cdnsp-gadget.h | 3 +++
 drivers/usb/cdns3/cdnsp-ring.c   | 3 ++-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/cdns3/cdnsp-gadget.c b/drivers/usb/cdns3/cdnsp-gadget.c
index 87f310841735..e64c8f7eb0c5 100644
--- a/drivers/usb/cdns3/cdnsp-gadget.c
+++ b/drivers/usb/cdns3/cdnsp-gadget.c
@@ -1773,6 +1773,8 @@ static void cdnsp_get_rev_cap(struct cdnsp_device *pdev)
 	reg += cdnsp_find_next_ext_cap(reg, 0, RTL_REV_CAP);
 	pdev->rev_cap  = reg;
 
+	pdev->rtl_revision = readl(&pdev->rev_cap->rtl_revision);
+
 	dev_info(pdev->dev, "Rev: %08x/%08x, eps: %08x, buff: %08x/%08x\n",
 		 readl(&pdev->rev_cap->ctrl_revision),
 		 readl(&pdev->rev_cap->rtl_revision),
diff --git a/drivers/usb/cdns3/cdnsp-gadget.h b/drivers/usb/cdns3/cdnsp-gadget.h
index 84887dfea763..357ddbe53917 100644
--- a/drivers/usb/cdns3/cdnsp-gadget.h
+++ b/drivers/usb/cdns3/cdnsp-gadget.h
@@ -1357,6 +1357,7 @@ struct cdnsp_port {
  * @rev_cap: Controller Capabilities Registers.
  * @hcs_params1: Cached register copies of read-only HCSPARAMS1
  * @hcc_params: Cached register copies of read-only HCCPARAMS1
+ * @rtl_revision: Cached controller rtl revision.
  * @setup: Temporary buffer for setup packet.
  * @ep0_preq: Internal allocated request used during enumeration.
  * @ep0_stage: ep0 stage during enumeration process.
@@ -1411,6 +1412,8 @@ struct cdnsp_device {
 	__u32 hcs_params1;
 	__u32 hcs_params3;
 	__u32 hcc_params;
+	#define RTL_REVISION_NEW_LPM 0x2700
+	__u32 rtl_revision;
 	/* Lock used in interrupt thread context. */
 	spinlock_t lock;
 	struct usb_ctrlrequest setup;
diff --git a/drivers/usb/cdns3/cdnsp-ring.c b/drivers/usb/cdns3/cdnsp-ring.c
index 46852529499d..fd06cb85c4ea 100644
--- a/drivers/usb/cdns3/cdnsp-ring.c
+++ b/drivers/usb/cdns3/cdnsp-ring.c
@@ -308,7 +308,8 @@ static bool cdnsp_ring_ep_doorbell(struct cdnsp_device *pdev,
 
 	writel(db_value, reg_addr);
 
-	cdnsp_force_l0_go(pdev);
+	if (pdev->rtl_revision < RTL_REVISION_NEW_LPM)
+		cdnsp_force_l0_go(pdev);
 
 	/* Doorbell was set. */
 	return true;
-- 
2.43.0