From: Ming Lei <tom.leiming@xxxxxxxxx> 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@xxxxxxxxx> --- This patch is against 2.6.37-rc2 and Hema's patch with title below: usb: musb: Unmapping the dma buffer when switching to PIO mode --- drivers/usb/musb/musb_gadget.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c index 0169dcf..7966c78 100644 --- a/drivers/usb/musb/musb_gadget.c +++ b/drivers/usb/musb/musb_gadget.c @@ -768,7 +768,7 @@ static void rxstate(struct musb *musb, struct musb_request *req) /* Clear DMAENAB for the * PIO mode transfer */ - csr &= ~MUSB_RXCSR_DMAENAB; + csr &= ~(MUSB_RXCSR_DMAENAB | MUSB_RXCSR_AUTOCLEAR); musb_writew(epio, MUSB_RXCSR, csr); } -- 1.7.3 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
