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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-kernel@vger.kernel.org>, <linux-usb@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 v7 04/33] usb: host: xhci-mem: Cleanup pending secondary event ring events
Date:   Thu, 21 Sep 2023 14:48:14 -0700
Message-ID: <20230921214843.18450-5-quic_wcheng@quicinc.com>
In-Reply-To: <20230921214843.18450-1-quic_wcheng@quicinc.com>
References: <20230921214843.18450-1-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 updating the
dequeue pointer to the last pending event trb.

Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
---
 drivers/usb/host/xhci-mem.c  |  9 ++++---
 drivers/usb/host/xhci-ring.c | 46 ++++++++++++++++++++++++++++++++++++
 drivers/usb/host/xhci.c      |  2 +-
 drivers/usb/host/xhci.h      |  3 +++
 4 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 2f9228d7d22d..94cbc25e77ca 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1801,7 +1801,6 @@ xhci_free_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
 {
 	struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
 	size_t erst_size;
-	u64 tmp64;
 	u32 tmp;
 
 	if (!ir)
@@ -1823,10 +1822,6 @@ xhci_free_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
 		tmp = readl(&ir->ir_set->erst_size);
 		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);
 	}
 
 	/* free interrrupter event ring */
@@ -1851,6 +1846,10 @@ void xhci_remove_secondary_interrupter(struct usb_hcd *hcd, struct xhci_interrup
 	/* fixme, should we check xhci->interrupter[intr_num] == ir */
 	spin_lock(&xhci->lock);
 	intr_num = ir->intr_num;
+
+	/* cleanup secondary interrupter to ensure there are no pending events */
+	xhci_skip_sec_intr_events(xhci, ir->event_ring, ir);
+
 	xhci_free_interrupter(xhci, ir);
 	xhci->interrupters[intr_num] = NULL;
 	spin_unlock(&xhci->lock);
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 93233cf5ff21..fdef1b82b1ff 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3026,6 +3026,52 @@ 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;
+	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 163d533d6200..2bb7895c1cd6 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 15ade8ec6b6c..e2133f125974 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -2029,6 +2029,9 @@ struct xhci_container_ctx *xhci_alloc_container_ctx(struct xhci_hcd *xhci,
 		int type, gfp_t flags);
 void xhci_free_container_ctx(struct xhci_hcd *xhci,
 		struct xhci_container_ctx *ctx);
+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 *);