linux-kernel - [PATCH v14 18/53] usb: host: xhci-mem: Cleanup pending secondary event ring events

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Date: Thu, 8 Feb 2024 15:13:31 -0800
From: Wesley Cheng <quic_wcheng@...cinc.com>
To: <srinivas.kandagatla@...aro.org>, <mathias.nyman@...el.com>,
        <perex@...ex.cz>, <conor+dt@...nel.org>, <corbet@....net>,
        <lgirdwood@...il.com>, <andersson@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <gregkh@...uxfoundation.org>,
        <Thinh.Nguyen@...opsys.com>, <broonie@...nel.org>,
        <bgoswami@...cinc.com>, <tiwai@...e.com>, <robh+dt@...nel.org>,
        <konrad.dybcio@...aro.org>
CC: <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-sound@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <alsa-devel@...a-project.org>, Wesley Cheng <quic_wcheng@...cinc.com>
Subject: [PATCH v14 18/53] usb: host: xhci-mem: Cleanup pending secondary event ring events

As part of xHCI bus suspend, the XHCI is halted.  However, if there are
pending events in the secondary event ring, it is observed that the xHCI
controller stops responding to further commands upon host or device
initiated bus resume.  Iterate through all pending events and update the
dequeue pointer to the beginning of the event ring.

Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
---
 drivers/usb/host/xhci-mem.c  |  7 ++++++-
 drivers/usb/host/xhci-ring.c | 33 ++++++++++++++++++++++++++++++++-
 drivers/usb/host/xhci.h      |  5 +++++
 3 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 450adaca68ee..e4c13f056c1a 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1827,7 +1827,7 @@ xhci_remove_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
 		tmp &= ERST_SIZE_MASK;
 		writel(tmp, &ir->ir_set->erst_size);
 
-		xhci_write_64(xhci, ERST_EHB, &ir->ir_set->erst_dequeue);
+		xhci_update_erst_dequeue(xhci, ir, true);
 	}
 }
 
@@ -1870,6 +1870,11 @@ void xhci_remove_secondary_interrupter(struct usb_hcd *hcd, struct xhci_interrup
 		return;
 	}
 
+	/*
+	 * Cleanup secondary interrupter to ensure there are no pending events.
+	 * This also updates event ring dequeue pointer back to the start.
+	 */
+	xhci_skip_sec_intr_events(xhci, ir->event_ring, ir);
 	intr_num = ir->intr_num;
 
 	xhci_remove_interrupter(xhci, ir);
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 958d6fd6d156..bdd88dcd0ad3 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2973,7 +2973,7 @@ static int xhci_handle_event_trb(struct xhci_hcd *xhci, struct xhci_interrupter
  * - When all events have finished
  * - To avoid "Event Ring Full Error" condition
  */
-static void xhci_update_erst_dequeue(struct xhci_hcd *xhci,
+void xhci_update_erst_dequeue(struct xhci_hcd *xhci,
 				     struct xhci_interrupter *ir,
 				     bool clear_ehb)
 {
@@ -3073,6 +3073,37 @@ static int xhci_handle_events(struct xhci_hcd *xhci, struct xhci_interrupter *ir
 	return 0;
 }
 
+/*
+ * Move the event ring dequeue pointer to skip events kept in the secondary
+ * event ring.  This is used to ensure that pending events in the ring are
+ * acknowledged, so the XHCI HCD can properly enter suspend/resume.  The
+ * secondary ring is typically maintained by an external component.
+ */
+void xhci_skip_sec_intr_events(struct xhci_hcd *xhci,
+	struct xhci_ring *ring,	struct xhci_interrupter *ir)
+{
+	union xhci_trb *current_trb;
+	u64 erdp_reg;
+	dma_addr_t deq;
+
+	/* disable irq, ack pending interrupt and ack all pending events */
+	xhci_disable_interrupter(ir);
+
+	/* last acked event trb is in erdp reg  */
+	erdp_reg = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
+	deq = (dma_addr_t)(erdp_reg & ERST_PTR_MASK);
+	if (!deq) {
+		xhci_err(xhci, "event ring handling not required\n");
+		return;
+	}
+
+	current_trb = ir->event_ring->dequeue;
+	/* read cycle state of the last acked trb to find out CCS */
+	ring->cycle_state = le32_to_cpu(current_trb->event_cmd.flags) & TRB_CYCLE;
+
+	xhci_handle_events(xhci, ir);
+}
+
 /*
  * xHCI spec says we can get an interrupt, and if the HC has an error condition,
  * we might get bad data out of the event ring.  Section 4.10.2.7 has a list of
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 0a4d9449bdff..96f9d1b38ff5 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1839,6 +1839,8 @@ struct xhci_interrupter *
 xhci_create_secondary_interrupter(struct usb_hcd *hcd, int num_seg);
 void xhci_remove_secondary_interrupter(struct usb_hcd
 				       *hcd, struct xhci_interrupter *ir);
+void xhci_skip_sec_intr_events(struct xhci_hcd *xhci,
+	struct xhci_ring *ring,	struct xhci_interrupter *ir);
 
 /* xHCI host controller glue */
 typedef void (*xhci_get_quirks_t)(struct device *, struct xhci_hcd *);
@@ -1930,6 +1932,9 @@ void inc_deq(struct xhci_hcd *xhci, struct xhci_ring *ring);
 unsigned int count_trbs(u64 addr, u64 len);
 int xhci_stop_endpoint_sync(struct xhci_hcd *xhci, struct xhci_virt_ep *ep,
 			    int suspend, gfp_t gfp_flags);
+void xhci_update_erst_dequeue(struct xhci_hcd *xhci,
+				     struct xhci_interrupter *ir,
+				     bool clear_ehb);
 
 /* xHCI roothub code */
 void xhci_set_link_state(struct xhci_hcd *xhci, struct xhci_port *port,