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Groups > linux.kernel > #1317528

[PATCH v6 07/12] usb: dbc: handle dbc-configured exit

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DbC might exit configured state in some cases (refer to 7.6.4.4 in
xHCI spec 1.1). Software needs detect and clear this situation by
clearing DCCTRL.DCR and wait until the DbC configured before read
or write oprations.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index f59c80ef..c81df40 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -1140,6 +1140,29 @@ static int xdbc_wait_until_bulk_done(struct xdbc_trb *trb, int loops)
 	return -EIO;
 }
 
+static int xdbc_wait_until_dbc_configured(void)
+{
+	int timeout = 0;
+	u32 reg;
+
+	/* Port exits configured state */
+	reg = readl(&xdbcp->xdbc_reg->control);
+	if (!(reg & CTRL_DRC))
+		return 0;
+
+	/* clear run change bit (RW1C) */
+	writel(reg | CTRL_DRC, &xdbcp->xdbc_reg->control);
+
+	do {
+		if (readl(&xdbcp->xdbc_reg->control) & CTRL_DCR)
+			return 0;
+
+		xdbc_udelay(10);
+	} while (timeout++ < XDBC_LOOPS);
+
+	return -ETIMEDOUT;
+}
+
 static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
 {
 	u64 addr;
@@ -1154,6 +1177,11 @@ static int xdbc_bulk_transfer(void *data, int size, int loops, bool read)
 		return -EINVAL;
 	}
 
+	if (xdbc_wait_until_dbc_configured()) {
+		xdbc_trace("%s: hardware not ready\n", __func__);
+		return -EPERM;
+	}
+
 	ring = (read ? &xdbcp->in_ring : &xdbcp->out_ring);
 	trb = ring->enqueue;
 	cycle = ring->cycle_state;
-- 
2.1.4

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[PATCH v6 00/12] usb: early: add support for early printk through USB3 debug port Lu Baolu <baolu.lu@linux.intel.com> - 2016-01-26 05:20 +0100
  [PATCH v6 07/12] usb: dbc: handle dbc-configured exit Lu Baolu <baolu.lu@linux.intel.com> - 2016-01-26 05:20 +0100
  [PATCH v6 11/12] usb: serial: usb_debug: add support for dbc debug device Lu Baolu <baolu.lu@linux.intel.com> - 2016-01-26 05:20 +0100
  [PATCH v6 02/12] x86: fixmap: add permanent fixmap for xhci debug port Lu Baolu <baolu.lu@linux.intel.com> - 2016-01-26 05:20 +0100
  [PATCH v6 12/12] usb: doc: add document for xHCI DbC driver Lu Baolu <baolu.lu@linux.intel.com> - 2016-01-26 05:20 +0100

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