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path: root/drivers/usb/musb/musb_host.c
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Diffstat (limited to 'drivers/usb/musb/musb_host.c')
-rw-r--r--drivers/usb/musb/musb_host.c22
1 files changed, 16 insertions, 6 deletions
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 26c65e66cc0f..795a45b1b25b 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -112,22 +112,32 @@ static void musb_h_tx_flush_fifo(struct musb_hw_ep *ep)
struct musb *musb = ep->musb;
void __iomem *epio = ep->regs;
u16 csr;
- u16 lastcsr = 0;
int retries = 1000;
csr = musb_readw(epio, MUSB_TXCSR);
while (csr & MUSB_TXCSR_FIFONOTEMPTY) {
- if (csr != lastcsr)
- dev_dbg(musb->controller, "Host TX FIFONOTEMPTY csr: %02x\n", csr);
- lastcsr = csr;
csr |= MUSB_TXCSR_FLUSHFIFO | MUSB_TXCSR_TXPKTRDY;
musb_writew(epio, MUSB_TXCSR, csr);
csr = musb_readw(epio, MUSB_TXCSR);
- if (WARN(retries-- < 1,
+
+ /*
+ * FIXME: sometimes the tx fifo flush failed, it has been
+ * observed during device disconnect on AM335x.
+ *
+ * To reproduce the issue, ensure tx urb(s) are queued when
+ * unplug the usb device which is connected to AM335x usb
+ * host port.
+ *
+ * I found using a usb-ethernet device and running iperf
+ * (client on AM335x) has very high chance to trigger it.
+ *
+ * Better to turn on dev_dbg() in musb_cleanup_urb() with
+ * CPPI enabled to see the issue when aborting the tx channel.
+ */
+ if (dev_WARN_ONCE(musb->controller, retries-- < 1,
"Could not flush host TX%d fifo: csr: %04x\n",
ep->epnum, csr))
return;
- mdelay(1);
}
}
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