diff options
| author | Ming Lei <tom.leiming@gmail.com> | 2010-11-16 16:37:37 +0100 |
|---|---|---|
| committer | Felipe Balbi <balbi@ti.com> | 2010-11-22 11:36:49 +0100 |
| commit | e75df37165c639b06213ec88b4763c3e50a7f079 (patch) | |
| tree | 100a2a07cccb4c1d2e956b3ec4182fda40777772 /drivers/usb | |
| parent | usb: musb: unmap dma buffer when switching to PIO (diff) | |
| download | linux-e75df37165c639b06213ec88b4763c3e50a7f079.tar.xz linux-e75df37165c639b06213ec88b4763c3e50a7f079.zip | |
usb: musb: clear RXCSR_AUTOCLEAR before PIO read
If RXCSR_AUTOCLEAR flag is not cleard before PIO reading, one packet
may be recieved by musb fifo, but no chance to notify
software, so cause packet loss, follows the detailed process:
- PIO read one packet
- musb fifo auto clear the MUSB_RXCSR_RXPKTRDY
- musb continue to recieve the next packet, and MUSB_RXCSR_RXPKTRDY
is set
- software clear the MUSB_RXCSR_RXPKTRDY, so there is no chance for
musb to notify software that the 2nd recieved packet.
The patch does fix the g_ether issue below:
- use fifo_mode 3 to enable double buffer
- 'ping -s 1024 IP_OF_BEAGLE_XM'
- one usb packet of 512 byte is lost, so ping failed,
which can be observed by wireshark
note:
Beagle xm takes musb rtl1.8 and may fallback to pio mode
for unaligned buffer.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Diffstat (limited to 'drivers/usb')
| -rw-r--r-- | drivers/usb/musb/musb_gadget.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c index 0169dcf3a6ff..363cfad003f8 100644 --- a/drivers/usb/musb/musb_gadget.c +++ b/drivers/usb/musb/musb_gadget.c @@ -765,10 +765,11 @@ static void rxstate(struct musb *musb, struct musb_request *req) if (is_dma_capable() && musb_ep->dma) { unmap_dma_buffer(req, musb); - /* Clear DMAENAB for the + /* + * Clear DMAENAB and AUTOCLEAR for the * PIO mode transfer */ - csr &= ~MUSB_RXCSR_DMAENAB; + csr &= ~(MUSB_RXCSR_DMAENAB | MUSB_RXCSR_AUTOCLEAR); musb_writew(epio, MUSB_RXCSR, csr); } |