linux-kernel - [PATCH] usb: dwc3: core: Disable USB2.0 phy suspend when dwc3 acts as host role

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Date:   Tue, 15 Nov 2016 17:41:20 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     balbi@...nel.org
Cc:     gregkh@...uxfoundation.org, broonie@...nel.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        baolin.wang@...aro.org
Subject: [PATCH] usb: dwc3: core: Disable USB2.0 phy suspend when dwc3 acts as host role

When dwc3 controller acts as host role with attaching slow speed device
(like mouse or keypad). Then if we plugged out the slow speed device,
it will timeout to run the deconfiguration endpoint command to drop the
endpoint's resources. Some xHCI command timeout log as below when
disconnecting one slow device:

[   99.807739] c0 xhci-hcd.0.auto: Port Status Change Event for port 1
[   99.814699] c0 xhci-hcd.0.auto: resume root hub
[   99.819992] c0 xhci-hcd.0.auto: handle_port_status: starting port
				   polling.
[   99.827808] c0 xhci-hcd.0.auto: get port status, actual port 0 status
				   = 0x202a0
[   99.835903] c0 xhci-hcd.0.auto: Get port status returned 0x10100
[   99.850052] c0 xhci-hcd.0.auto: clear port connect change, actual
				   port 0 status  = 0x2a0
[   99.859313] c0 xhci-hcd.0.auto: Cancel URB ffffffc01ed6cd00, dev 1,
				   ep 0x81, starting at offset 0xc406d210
[   99.869645] c0 xhci-hcd.0.auto: // Ding dong!
[   99.874776] c0 xhci-hcd.0.auto: Stopped on Transfer TRB
[   99.880713] c0 xhci-hcd.0.auto: Removing canceled TD starting at
				   0xc406d210 (dma).
[   99.889012] c0 xhci-hcd.0.auto: Finding endpoint context
[   99.895069] c0 xhci-hcd.0.auto: Cycle state = 0x1
[   99.900519] c0 xhci-hcd.0.auto: New dequeue segment =
				   ffffffc1112f0880 (virtual)
[   99.908655] c0 xhci-hcd.0.auto: New dequeue pointer = 0xc406d220 (DMA)
[   99.915927] c0 xhci-hcd.0.auto: Set TR Deq Ptr cmd, new deq seg =
				   ffffffc1112f0880 (0xc406d000 dma),
				   new deq ptr = ffffff8002175220
				   (0xc406d220 dma), new cycle = 1
[   99.931242] c0 xhci-hcd.0.auto: // Ding dong!
[   99.936360] c0 xhci-hcd.0.auto: Successful Set TR Deq Ptr cmd,
				   deq = @c406d220
[   99.944458] c0 xhci-hcd.0.auto: xhci_hub_status_data: stopping port
				   polling.
[  100.047619] c0 xhci-hcd.0.auto: xhci_drop_endpoint called for udev
				   ffffffc01ae08800
[  100.057002] c0 xhci-hcd.0.auto: drop ep 0x81, slot id 1, new drop
				   flags = 0x8, new add flags = 0x0
[  100.067878] c0 xhci-hcd.0.auto: xhci_check_bandwidth called for udev
				   ffffffc01ae08800
[  100.076868] c0 xhci-hcd.0.auto: New Input Control Context:

......

[  100.427252] c0 xhci-hcd.0.auto: // Ding dong!
[  105.430728] c0 xhci-hcd.0.auto: Command timeout
[  105.436029] c0 xhci-hcd.0.auto: Abort command ring
[  113.558223] c0 xhci-hcd.0.auto: Command completion event does not match
				   command
[  113.569778] c0 xhci-hcd.0.auto: Timeout while waiting for configure
				   endpoint command

The reason is it will suspend USB phy to disable phy clock when
disconnecting the slow USB decice, that will hang on the xHCI commands
executing which depends on the phy clock.

Thus we should disable USB2.0 phy suspend feature when dwc3 acts as host
role.

Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
---
 drivers/usb/dwc3/core.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 9a4a5e4..0b646cf 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -565,6 +565,20 @@ static int dwc3_phy_setup(struct dwc3 *dwc)
 	if (dwc->revision > DWC3_REVISION_194A)
 		reg |= DWC3_GUSB2PHYCFG_SUSPHY;
 
+	/*
+	 * When dwc3 controller acts as host role with attaching one slow speed
+	 * device (like mouse or keypad). Then if we plugged out the slow speed
+	 * device, it will timeout to run the deconfiguration endpoint command.
+	 * The reason is it will suspend USB phy to disable phy clock when
+	 * disconnecting slow speed decice, which will affect the xHCI commands
+	 * executing.
+	 *
+	 * Thus we should disable USB 2.0 phy suspend feature when dwc3 acts as
+	 * host role.
+	 */
+	if (dwc->dr_mode == USB_DR_MODE_HOST || dwc->dr_mode == USB_DR_MODE_OTG)
+		reg &= ~DWC3_GUSB2PHYCFG_SUSPHY;
+
 	if (dwc->dis_u2_susphy_quirk)
 		reg &= ~DWC3_GUSB2PHYCFG_SUSPHY;
 
-- 
1.7.9.5