usb: musb: Ensure rx reinit occurs for shared_fifo endpoints

[karo-tx-linux.git] / drivers / usb / musb / musb_host.c

diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 26c65e66cc0f1db8680933d13ed2d2b960603906..7955768d3b1a04e94442335e0f3c9908f3e0d55d 100644 (file)
--- 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);
        }
 }
 
@@ -584,14 +594,13 @@ musb_rx_reinit(struct musb *musb, struct musb_qh *qh, u8 epnum)
                musb_writew(ep->regs, MUSB_TXCSR, 0);
 
        /* scrub all previous state, clearing toggle */
-       } else {
-               csr = musb_readw(ep->regs, MUSB_RXCSR);
-               if (csr & MUSB_RXCSR_RXPKTRDY)
-                       WARNING("rx%d, packet/%d ready?\n", ep->epnum,
-                               musb_readw(ep->regs, MUSB_RXCOUNT));
-
-               musb_h_flush_rxfifo(ep, MUSB_RXCSR_CLRDATATOG);
        }
+       csr = musb_readw(ep->regs, MUSB_RXCSR);
+       if (csr & MUSB_RXCSR_RXPKTRDY)
+               WARNING("rx%d, packet/%d ready?\n", ep->epnum,
+                       musb_readw(ep->regs, MUSB_RXCOUNT));
+
+       musb_h_flush_rxfifo(ep, MUSB_RXCSR_CLRDATATOG);
 
        /* target addr and (for multipoint) hub addr/port */
        if (musb->is_multipoint) {
@@ -985,9 +994,15 @@ static void musb_bulk_nak_timeout(struct musb *musb, struct musb_hw_ep *ep,
        if (is_in) {
                dma = is_dma_capable() ? ep->rx_channel : NULL;
 
-               /* clear nak timeout bit */
+               /*
+                * Need to stop the transaction by clearing REQPKT first
+                * then the NAK Timeout bit ref MUSBMHDRC USB 2.0 HIGH-SPEED
+                * DUAL-ROLE CONTROLLER Programmer's Guide, section 9.2.2
+                */
                rx_csr = musb_readw(epio, MUSB_RXCSR);
                rx_csr |= MUSB_RXCSR_H_WZC_BITS;
+               rx_csr &= ~MUSB_RXCSR_H_REQPKT;
+               musb_writew(epio, MUSB_RXCSR, rx_csr);
                rx_csr &= ~MUSB_RXCSR_DATAERROR;
                musb_writew(epio, MUSB_RXCSR, rx_csr);