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Date:   Mon, 29 Apr 2019 20:31:05 +0800
From:   Jim Lin <jilin@...dia.com>
To:     <mathias.nyman@...el.com>, <gregkh@...uxfoundation.org>
CC:     <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Jim Lin <jilin@...dia.com>
Subject: [PATCH v2 1/1] usb: xhci: Add Clear_TT_Buffer

USB 2.0 specification chapter 11.17.5 says "as part of endpoint halt
processing for full-/low-speed endpoints connected via a TT, the host
software must use the Clear_TT_Buffer request to the TT to ensure
that the buffer is not in the busy state".

In our case, a full-speed speaker (ConferenceCam) is behind a high-
speed hub (ConferenceCam Connect), sometimes once we get STALL on a
request we may continue to get STALL with the folllowing requests,
like Set_Interface.

Here we add Clear_TT_Buffer for the following Set_Interface requests
to get ACK successfully.

Signed-off-by: Jim Lin <jilin@...dia.com>
---
v2: xhci_clear_tt_buffer_complete: add static, shorter indentation
    , remove its claiming in xhci.h

 drivers/usb/host/xhci-ring.c | 28 ++++++++++++++++++++++++++++
 drivers/usb/host/xhci.c      |  7 +++++++
 drivers/usb/host/xhci.h      |  1 +
 3 files changed, 36 insertions(+)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 9215a28dad40..02b1ebad81e7 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1786,6 +1786,33 @@ struct xhci_segment *trb_in_td(struct xhci_hcd *xhci,
 	return NULL;
 }
 
+static void xhci_clear_hub_tt_buffer(struct xhci_hcd *xhci,
+	unsigned int slot_id, struct xhci_td *td)
+{
+	struct xhci_virt_device *dev;
+	struct xhci_slot_ctx *slot_ctx;
+	int saved_devnum;
+
+	/*
+	 * As part of low/full-speed endpoint-halt processing
+	 * we must clear the TT buffer (USB 2.0 specification 11.17.5).
+	 */
+	if (td->urb->dev->tt && !usb_pipeint(td->urb->pipe) &&
+	    (td->urb->dev->tt->hub != xhci_to_hcd(xhci)->self.root_hub) &&
+	    !xhci->clearing_tt) {
+		xhci->clearing_tt = 1;
+		dev = xhci->devs[slot_id];
+		slot_ctx = xhci_get_slot_ctx(xhci, dev->out_ctx);
+		/* Update devnum temporarily for usb_hub_clear_tt_buffer */
+		saved_devnum = td->urb->dev->devnum;
+		td->urb->dev->devnum = (int) le32_to_cpu(slot_ctx->dev_state) &
+			DEV_ADDR_MASK;
+		if (usb_hub_clear_tt_buffer(td->urb))
+			xhci->clearing_tt = 0;
+		td->urb->dev->devnum = saved_devnum;
+	}
+}
+
 static void xhci_cleanup_halted_endpoint(struct xhci_hcd *xhci,
 		unsigned int slot_id, unsigned int ep_index,
 		unsigned int stream_id, struct xhci_td *td,
@@ -1804,6 +1831,7 @@ static void xhci_cleanup_halted_endpoint(struct xhci_hcd *xhci,
 	if (reset_type == EP_HARD_RESET) {
 		ep->ep_state |= EP_HARD_CLEAR_TOGGLE;
 		xhci_cleanup_stalled_ring(xhci, ep_index, stream_id, td);
+		xhci_clear_hub_tt_buffer(xhci, slot_id, td);
 	}
 	xhci_ring_cmd_db(xhci);
 }
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 7fa58c99f126..4890c3518aa3 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -5132,6 +5132,12 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
 }
 EXPORT_SYMBOL_GPL(xhci_gen_setup);
 
+static void xhci_clear_tt_buffer_complete(struct usb_hcd *hcd,
+		struct usb_host_endpoint *ep)
+{
+	hcd_to_xhci(hcd)->clearing_tt = 0;
+}
+
 static const struct hc_driver xhci_hc_driver = {
 	.description =		"xhci-hcd",
 	.product_desc =		"xHCI Host Controller",
@@ -5192,6 +5198,7 @@ static const struct hc_driver xhci_hc_driver = {
 	.enable_usb3_lpm_timeout =	xhci_enable_usb3_lpm_timeout,
 	.disable_usb3_lpm_timeout =	xhci_disable_usb3_lpm_timeout,
 	.find_raw_port_number =	xhci_find_raw_port_number,
+	.clear_tt_buffer_complete = xhci_clear_tt_buffer_complete,
 };
 
 void xhci_init_driver(struct hc_driver *drv,
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 9334cdee382a..87e9574a6102 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1864,6 +1864,7 @@ struct xhci_hcd {
 	unsigned		hw_lpm_support:1;
 	/* Broken Suspend flag for SNPS Suspend resume issue */
 	unsigned		broken_suspend:1;
+	unsigned		clearing_tt:1;
 	/* cached usb2 extened protocol capabilites */
 	u32                     *ext_caps;
 	unsigned int            num_ext_caps;
-- 
2.1.4

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