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From:   Wesley Cheng <quic_wcheng@quicinc.com>
To:     <mathias.nyman@intel.com>, <gregkh@linuxfoundation.org>,
        <lgirdwood@gmail.com>, <broonie@kernel.org>, <perex@perex.cz>,
        <tiwai@suse.com>, <agross@kernel.org>, <andersson@kernel.org>,
        <konrad.dybcio@linaro.org>, <robh+dt@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <conor+dt@kernel.org>,
        <srinivas.kandagatla@linaro.org>, <bgoswami@quicinc.com>,
        <Thinh.Nguyen@synopsys.com>
CC:     <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <alsa-devel@alsa-project.org>, <linux-arm-msm@vger.kernel.org>,
        <devicetree@vger.kernel.org>,
        Wesley Cheng <quic_wcheng@quicinc.com>
Subject: [PATCH v8 05/34] usb: host: xhci-mem: Cleanup pending secondary event ring events
Date:   Tue, 10 Oct 2023 17:21:17 -0700
Message-ID: <20231011002146.1821-6-quic_wcheng@quicinc.com>
In-Reply-To: <20231011002146.1821-1-quic_wcheng@quicinc.com>
References: <20231011002146.1821-1-quic_wcheng@quicinc.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

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@quicinc.com>
---
 drivers/usb/host/xhci-mem.c  | 13 +++++----
 drivers/usb/host/xhci-ring.c | 51 +++++++++++++++++++++++++++++++++++-
 drivers/usb/host/xhci.c      |  2 +-
 drivers/usb/host/xhci.h      |  6 +++++
 4 files changed, 63 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 908b8c9d5837..e6df1cb15e5b 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1815,9 +1815,7 @@ xhci_remove_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
 		tmp &= ERST_SIZE_MASK;
 		writel(tmp, &ir->ir_set->erst_size);
 
-		tmp64 = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
-		tmp64 &= (u64) ERST_PTR_MASK;
-		xhci_write_64(xhci, tmp64, &ir->ir_set->erst_dequeue);
+		xhci_update_erst_dequeue(xhci, ir, ir->event_ring->first_seg->trbs);
 	}
 }
 
@@ -1855,11 +1853,12 @@ void xhci_remove_secondary_interrupter(struct usb_hcd *hcd, struct xhci_interrup
 	if (!ir || !ir->intr_num || ir->intr_num >= xhci->max_interrupters)
 		xhci_dbg(xhci, "Invalid secondary interrupter, can't remove\n");
 
-	/* fixme, should we check xhci->interrupter[intr_num] == ir */
-	/* fixme locking */
-
 	spin_lock_irq(&xhci->lock);
-
+	/*
+	 * 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 93233cf5ff21..13080f82406a 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2994,7 +2994,7 @@ static int xhci_handle_event(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
  * - 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,
 				     union xhci_trb *event_ring_deq)
 {
@@ -3026,6 +3026,55 @@ static void xhci_update_erst_dequeue(struct xhci_hcd *xhci,
 	xhci_write_64(xhci, temp_64, &ir->ir_set->erst_dequeue);
 }
 
+/*
+ * 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 *erdp_trb, *current_trb;
+	struct xhci_segment	*seg;
+	u64 erdp_reg;
+	u32 iman_reg;
+	dma_addr_t deq;
+	unsigned long segment_offset;
+
+	/* disable irq, ack pending interrupt and ack all pending events */
+	xhci_disable_interrupter(ir);
+	iman_reg = readl_relaxed(&ir->ir_set->irq_pending);
+	if (iman_reg & IMAN_IP)
+		writel_relaxed(iman_reg, &ir->ir_set->irq_pending);
+
+	/* 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_dbg(xhci, "event ring handling not required\n");
+		return;
+	}
+
+	seg = ring->first_seg;
+	segment_offset = deq - seg->dma;
+
+	erdp_trb = 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;
+
+	while (1) {
+		inc_deq(xhci, ir->event_ring);
+		erdp_trb = ir->event_ring->dequeue;
+		/* cycle state transition */
+		if ((le32_to_cpu(erdp_trb->event_cmd.flags) & TRB_CYCLE) !=
+		    ring->cycle_state)
+			break;
+	}
+
+	xhci_update_erst_dequeue(xhci, ir, current_trb);
+}
+
 /*
  * 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.c b/drivers/usb/host/xhci.c
index 6465acca7c79..f947526ce3ff 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -309,7 +309,7 @@ static int xhci_enable_interrupter(struct xhci_interrupter *ir)
 	return 0;
 }
 
-static int xhci_disable_interrupter(struct xhci_interrupter *ir)
+int xhci_disable_interrupter(struct xhci_interrupter *ir)
 {
 	u32 iman;
 
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index ce482267e219..9ef375e5c27e 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -2095,6 +2095,9 @@ void xhci_free_container_ctx(struct xhci_hcd *xhci,
 struct xhci_interrupter *xhci_create_secondary_interrupter(struct usb_hcd *hcd);
 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);
+int xhci_disable_interrupter(struct xhci_interrupter *ir);
 
 /* xHCI host controller glue */
 typedef void (*xhci_get_quirks_t)(struct device *, struct xhci_hcd *);
@@ -2180,6 +2183,9 @@ 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,
+				     union xhci_trb *event_ring_deq);
 
 /* xHCI roothub code */
 void xhci_set_link_state(struct xhci_hcd *xhci, struct xhci_port *port,