[PATCH 1/3] xhci: Workaround to get Intel xHCI reset working more reliably

[PATCH 1/3] xhci: Workaround to get Intel xHCI reset working more reliably

[Mathias Nyman]

From: Rajmohan Mani <rajmohan.mani@intel.com>

Existing Intel xHCI controllers require a delay of 1 mS,
after setting the CMD_RESET bit in command register, before
accessing any HC registers. This allows the HC to complete
the reset operation and be ready for HC register access.
Without this delay, the subsequent HC register access,
may result in a system hang, very rarely.

Verified CherryView / Braswell platforms go through over
5000 warm reboot cycles (which was not possible without
this patch), without any xHCI reset hang.

Signed-off-by: Rajmohan Mani <rajmohan.mani@intel.com>
Tested-by: Joe Lawrence <joe.lawrence@stratus.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 6e7dc6f..dfa44d3 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -175,6 +175,16 @@ int xhci_reset(struct xhci_hcd *xhci)
 	command |= CMD_RESET;
 	writel(command, &xhci->op_regs->command);
 
+	/* Existing Intel xHCI controllers require a delay of 1 mS,
+	 * after setting the CMD_RESET bit, and before accessing any
+	 * HC registers. This allows the HC to complete the
+	 * reset operation and be ready for HC register access.
+	 * Without this delay, the subsequent HC register access,
+	 * may result in a system hang very rarely.
+	 */
+	if (xhci->quirks & XHCI_INTEL_HOST)
+		udelay(1000);
+
 	ret = xhci_handshake(&xhci->op_regs->command,
 			CMD_RESET, 0, 10 * 1000 * 1000);
 	if (ret)
-- 
1.9.1

[PATCH 2/3] usb: xhci: fix checking ep busy for CFC

[Mathias Nyman]

From: Lu Baolu <baolu.lu@linux.intel.com>

Function ep_ring_is_processing() checks the dequeue pointer
in endpoint context to know whether an endpoint is busy with
processing TRBs. This is not correct since dequeue pointer
field in an endpoint context is only valid when the endpoint
is in Halted or Stopped states. This buggy code causes audio
noise when playing sound with USB headset connected to host
controllers which support CFC (one of xhci 1.1 features).

This patch should exist in stable kernel since v4.3.

Reported-and-tested-by: YD Tseng <yd_tseng@asmedia.com.tw>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Cc: stable <stable@vger.kernel.org> # v4.3
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci-ring.c | 32 ++++++--------------------------
 1 file changed, 6 insertions(+), 26 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index fa83625..6c5e813 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3896,28 +3896,6 @@ cleanup:
 	return ret;
 }
 
-static int ep_ring_is_processing(struct xhci_hcd *xhci,
-		int slot_id, unsigned int ep_index)
-{
-	struct xhci_virt_device *xdev;
-	struct xhci_ring *ep_ring;
-	struct xhci_ep_ctx *ep_ctx;
-	struct xhci_virt_ep *xep;
-	dma_addr_t hw_deq;
-
-	xdev = xhci->devs[slot_id];
-	xep = &xhci->devs[slot_id]->eps[ep_index];
-	ep_ring = xep->ring;
-	ep_ctx = xhci_get_ep_ctx(xhci, xdev->out_ctx, ep_index);
-
-	if ((le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK) != EP_STATE_RUNNING)
-		return 0;
-
-	hw_deq = le64_to_cpu(ep_ctx->deq) & ~EP_CTX_CYCLE_MASK;
-	return (hw_deq !=
-		xhci_trb_virt_to_dma(ep_ring->enq_seg, ep_ring->enqueue));
-}
-
 /*
  * Check transfer ring to guarantee there is enough room for the urb.
  * Update ISO URB start_frame and interval.
@@ -3983,10 +3961,12 @@ int xhci_queue_isoc_tx_prepare(struct xhci_hcd *xhci, gfp_t mem_flags,
 	}
 
 	/* Calculate the start frame and put it in urb->start_frame. */
-	if (HCC_CFC(xhci->hcc_params) &&
-			ep_ring_is_processing(xhci, slot_id, ep_index)) {
-		urb->start_frame = xep->next_frame_id;
-		goto skip_start_over;
+	if (HCC_CFC(xhci->hcc_params) && !list_empty(&ep_ring->td_list)) {
+		if ((le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK) ==
+				EP_STATE_RUNNING) {
+			urb->start_frame = xep->next_frame_id;
+			goto skip_start_over;
+		}
 	}
 
 	start_frame = readl(&xhci->run_regs->microframe_index);
-- 
1.9.1

[PATCH 3/3] xhci: Fix a race in usb2 LPM resume, blocking U3 for usb2 devices

[Mathias Nyman]

Clear device initiated resume variables once device is fully up and running
in U0 state.

Resume needs to be signaled for 20ms for usb2 devices before they can be
moved to U0 state.

An interrupt is triggered if a device initiates resume. As we handle the
event in interrupt context we can not sleep for 20ms, so we instead set
a resume flag, a timestamp, and start the roothub polling.

The roothub code will later move the port to U0 when it finds a port in
resume state with the resume flag set, and timestamp passed by 20ms.

A host initiated resume is however not done in interrupt context, and
host initiated resume code will directly signal resume, wait 20ms and then
move the port to U0.

These two codepaths can race, if we are in the middle of a host initated
resume, while sleeping for 20ms, we may handle a port event and find the
port in resume state. The port event handling code will assume the resume
was device initiated and set the resume flag and timestamp.

Root hub code will however not catch the port in resume state again as the
host initated resume code has already moved the port to U0.
The resume flag and timestamp will remain set for this port preventing port
from suspending again  (LPM setting port to U3)

Fix this for now by always clearing the device initated resume parameters
once port is in U0

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
---
 drivers/usb/host/xhci-hub.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 5d2d7e9..0230965 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -782,12 +782,15 @@ static u32 xhci_get_port_status(struct usb_hcd *hcd,
 			status |= USB_PORT_STAT_SUSPEND;
 		}
 	}
-	if ((raw_port_status & PORT_PLS_MASK) == XDEV_U0
-			&& (raw_port_status & PORT_POWER)
-			&& (bus_state->suspended_ports & (1 << wIndex))) {
-		bus_state->suspended_ports &= ~(1 << wIndex);
-		if (hcd->speed < HCD_USB3)
-			bus_state->port_c_suspend |= 1 << wIndex;
+	if ((raw_port_status & PORT_PLS_MASK) == XDEV_U0 &&
+	    (raw_port_status & PORT_POWER)) {
+		if (bus_state->suspended_ports & (1 << wIndex)) {
+			bus_state->suspended_ports &= ~(1 << wIndex);
+			if (hcd->speed < HCD_USB3)
+				bus_state->port_c_suspend |= 1 << wIndex;
+		}
+		bus_state->resume_done[wIndex] = 0;
+		clear_bit(wIndex, &bus_state->resuming_ports);
 	}
 	if (raw_port_status & PORT_CONNECT) {
 		status |= USB_PORT_STAT_CONNECTION;
-- 
1.9.1