linux-kernel - [PATCH v2 4/4] xhci: Add zhaoxin xHCI U1/U2 feature support

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Message-ID: <20230421203853.387210-5-WeitaoWang-oc@zhaoxin.com>
Date:   Sat, 22 Apr 2023 04:38:53 +0800
From:   Weitao Wang <WeitaoWang-oc@...oxin.com>
To:     <gregkh@...uxfoundation.org>, <mathias.nyman@...el.com>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <tonywwang@...oxin.com>, <weitaowang@...oxin.com>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>,
        <stable@...r.kernel.org>
Subject: [PATCH v2 4/4] xhci: Add zhaoxin xHCI U1/U2 feature support

Add U1/U2 feature support of xHCI for zhaoxin.
Since both Intel and Zhaoxin need to check the tier where the device is
located to determine whether to enabled U1/U2, remove the previous Intel
U1/U2 tier policy and add common policy in xhci_check_tier_policy.
If vendor has specific U1/U2 enable policy,quirks can be add to declare.

Suggested-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc: stable@...r.kernel.org
Signed-off-by: Weitao Wang <WeitaoWang-oc@...oxin.com>
---
 v1->v2
 - Modify the description.
 - Adjust U1/U2 tier enable policy.

 drivers/usb/host/xhci.c | 43 +++++++++++++++++------------------------
 1 file changed, 18 insertions(+), 25 deletions(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 31d6ace9cace..b81a69126188 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4802,7 +4802,7 @@ static u16 xhci_calculate_u1_timeout(struct xhci_hcd *xhci,
 		}
 	}
 
-	if (xhci->quirks & XHCI_INTEL_HOST)
+	if (xhci->quirks & (XHCI_INTEL_HOST | XHCI_ZHAOXIN_HOST))
 		timeout_ns = xhci_calculate_intel_u1_timeout(udev, desc);
 	else
 		timeout_ns = udev->u1_params.sel;
@@ -4866,7 +4866,7 @@ static u16 xhci_calculate_u2_timeout(struct xhci_hcd *xhci,
 		}
 	}
 
-	if (xhci->quirks & XHCI_INTEL_HOST)
+	if (xhci->quirks & (XHCI_INTEL_HOST | XHCI_ZHAOXIN_HOST))
 		timeout_ns = xhci_calculate_intel_u2_timeout(udev, desc);
 	else
 		timeout_ns = udev->u2_params.sel;
@@ -4938,37 +4938,30 @@ static int xhci_update_timeout_for_interface(struct xhci_hcd *xhci,
 	return 0;
 }
 
-static int xhci_check_intel_tier_policy(struct usb_device *udev,
+static int xhci_check_tier_policy(struct xhci_hcd *xhci,
+		struct usb_device *udev,
 		enum usb3_link_state state)
 {
-	struct usb_device *parent;
-	unsigned int num_hubs;
+	struct usb_device *parent = udev->parent;
+	int tier = 1; /* roothub is tier1 */
 
-	/* Don't enable U1 if the device is on a 2nd tier hub or lower. */
-	for (parent = udev->parent, num_hubs = 0; parent->parent;
-			parent = parent->parent)
-		num_hubs++;
+	while (parent) {
+		parent = parent->parent;
+		tier++;
+	}
 
-	if (num_hubs < 2)
-		return 0;
+	if (xhci->quirks & XHCI_INTEL_HOST && tier > 3)
+		goto fail;
+	if (xhci->quirks & XHCI_ZHAOXIN_HOST && tier > 2)
+		goto fail;
 
-	dev_dbg(&udev->dev, "Disabling U1/U2 link state for device"
-			" below second-tier hub.\n");
-	dev_dbg(&udev->dev, "Plug device into first-tier hub "
-			"to decrease power consumption.\n");
+	return 0;
+fail:
+	dev_dbg(&udev->dev, "Tier policy prevents U1/U2 LPM states for devices at tier %d\n",
+			tier);
 	return -E2BIG;
 }
 
-static int xhci_check_tier_policy(struct xhci_hcd *xhci,
-		struct usb_device *udev,
-		enum usb3_link_state state)
-{
-	if (xhci->quirks & XHCI_INTEL_HOST)
-		return xhci_check_intel_tier_policy(udev, state);
-	else
-		return 0;
-}
-
 /* Returns the U1 or U2 timeout that should be enabled.
  * If the tier check or timeout setting functions return with a non-zero exit
  * code, that means the timeout value has been finalized and we shouldn't look
-- 
2.32.0