[PATCH] : omap-udc stressed full duplex usb communication.

[Marc Chalain <marc.chalain@myriadgroup.com>]

  Hello

I'm working on an Omap target:

CPU: ARM926EJ-S [41069263] revision 3 (ARMv5TEJ), cr=00053177
Machine: TI OMAP1710 HW20acq board
Memory policy: ECC disabled, Data cache writeback
OMAP1710 revision 8 handled as 16xx id: 8b5f702f03330200

I use the usb as cdc_acm and the communication in the both ways is very
stressed.
Some time the device receives a strange IRQ from EP0, which stop all
data reception from USB.
The usb registers during this IRQ are:
  IRQ_SRC : 0xB0
  EPN_STAT : 0x01
  EP_NUM : 0x11
  STAT_FLG : 0x00

The TI inc. documentation explains that the IRQ_SRC is TX and RX in the
same time. (the irq callback can manage only one). But EPN_STAT gives
only the EP number of the TX request.
In the same documentation we can read p15-67:
  11:8 EPn_RX_IT_SRC The receive endpoint interrupt source (non-ISO) bit
only concerns non-ISO enpoints...
  000: No receive endpoint interrupt is pending

I send you my patch. I hope that it will be usefull.

diff --git a/drivers/usb/gadget/omap_udc.c b/drivers/usb/gadget/omap_udc.c
index f81e4f0..863f692 100644
--- a/drivers/usb/gadget/omap_udc.c
+++ b/drivers/usb/gadget/omap_udc.c
@@ -1948,7 +1948,7 @@ static irqreturn_t omap_udc_pio_irq(int irq, void
*_dev)
         u16             epn_stat, irq_src;
         irqreturn_t     status = IRQ_NONE;
         struct omap_ep  *ep;
-       int             epnum;
+       int             epnum, epnumrx, epnumtx;
         struct omap_udc *udc = _dev;
         struct omap_req *req;
         unsigned long   flags;
@@ -1957,9 +1957,11 @@ static irqreturn_t omap_udc_pio_irq(int irq, void
*_dev)
         epn_stat = omap_readw(UDC_EPN_STAT);
         irq_src = omap_readw(UDC_IRQ_SRC);

+       epnumrx = (epn_stat >> 8) & 0x0f;
+       epnumtx = epn_stat & 0x0f;
         /* handle OUT first, to avoid some wasteful NAKs */
-       if (irq_src & UDC_EPN_RX) {
-               epnum = (epn_stat >> 8) & 0x0f;
+       if ((irq_src & UDC_EPN_RX) && epnumrx) {
+               epnum = epnumrx;
                 omap_writew(UDC_EPN_RX, UDC_IRQ_SRC);
                 status = IRQ_HANDLED;
                 ep = &udc->ep[epnum];
@@ -1994,8 +1996,8 @@ static irqreturn_t omap_udc_pio_irq(int irq, void
*_dev)
         }

         /* then IN transfers */
-       else if (irq_src & UDC_EPN_TX) {
-               epnum = epn_stat & 0x0f;
+       else if ((irq_src & UDC_EPN_TX) && epnumtx){
+               epnum = epnumtx;
                 omap_writew(UDC_EPN_TX, UDC_IRQ_SRC);
                 status = IRQ_HANDLED;
                 ep = &udc->ep[16 + epnum];


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