From 2188a9c6b5daa4003d3226d38a4b02d048d92b88 Mon Sep 17 00:00:00 2001 From: Antti P Miettinen Date: Fri, 3 Mar 2006 11:08:43 -0800 Subject: [PATCH] [PATCH] ARM: OMAP: USB gadget driver While doing development for an OMAP2420 board I noticed that the "workaround for seemingly-lost IRQs for RX ACKs" in omap_udc.c needs a little tweak in order to prevent NFS root over usbnet from hanging. According to the documentation the status flag register should only be accessed when endpoint select bit is set in the EP_NUM register. See e.g. SPRU761A, end of page 78 (about STAT_FLG register): "This register cannot be read if EP_NUM.EP_SEL bit is not asserted for the endpoint." Similar statement seems to be in the specs for other OMAPs too. As a change for the workaround seem to have an effect it seems that there is indeed an underlying "IRQs get lost" problem? In principle reading the status flag in proc_ep_show() would need similar change, but I'm not sure how the EP selection would interact with interrupt processing. Actually I'm not sure how this change interacts with interrupt processing either but at least it cured the hangs for the 2420. It seems that usbnet with Nokia 770 is also a bit unreliable but this change does not seem to have an effect. Does someone have an OMAP based system where usbnet is reliable? --- drivers/usb/gadget/omap_udc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/usb/gadget/omap_udc.c b/drivers/usb/gadget/omap_udc.c index 2b5afd7297a..f2b065fd28b 100644 --- a/drivers/usb/gadget/omap_udc.c +++ b/drivers/usb/gadget/omap_udc.c @@ -1905,7 +1905,7 @@ static void pio_out_timer(unsigned long _ep) spin_lock_irqsave(&ep->udc->lock, flags); if (!list_empty(&ep->queue) && ep->ackwait) { - use_ep(ep, 0); + use_ep(ep, UDC_EP_SEL); stat_flg = UDC_STAT_FLG_REG; if ((stat_flg & UDC_ACK) && (!(stat_flg & UDC_FIFO_EN) @@ -1915,12 +1915,14 @@ static void pio_out_timer(unsigned long _ep) VDBG("%s: lose, %04x\n", ep->ep.name, stat_flg); req = container_of(ep->queue.next, struct omap_req, queue); - UDC_EP_NUM_REG = ep->bEndpointAddress | UDC_EP_SEL; (void) read_fifo(ep, req); UDC_EP_NUM_REG = ep->bEndpointAddress; UDC_CTRL_REG = UDC_SET_FIFO_EN; ep->ackwait = 1 + ep->double_buf; } + else { + deselect_ep(); + } } mod_timer(&ep->timer, PIO_OUT_TIMEOUT); spin_unlock_irqrestore(&ep->udc->lock, flags); -- 2.41.1