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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>
This commit is contained in:
Ming Lei 2010-11-16 23:37:37 +08:00 committed by Felipe Balbi
parent 92d2711f5d
commit e75df37165
1 changed files with 3 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/usb/musb/musb_gadget.c
View File

@ -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);
}