Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964990Ab3DPPl7 (ORCPT ); Tue, 16 Apr 2013 11:41:59 -0400 Received: from mail-ee0-f45.google.com ([74.125.83.45]:44961 "EHLO mail-ee0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935563Ab3DPPl6 (ORCPT ); Tue, 16 Apr 2013 11:41:58 -0400 From: Ruslan Bilovol To: balbi@ti.com, gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] usb: musb: gadget: fix enumeration on heavy-loaded systems Date: Tue, 16 Apr 2013 18:41:44 +0300 Message-Id: <1366126904-31605-1-git-send-email-ruslan.bilovol@ti.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2680 Lines: 80 >From musb point of view, the Address Assignment sequence during device enumeration is next: - first ep0 interrupt: * read the address from USB_REQ_SET_ADDRESS request * set up CSR0L.DataEnd bit (that is ACK signalization for the host) - second ep0 interrupt: * indicates that the request completed successfully * set up musb device address Now musb device should answer to this address >From the host perspective, if peripheral device acquires SET_ADDRESS request, it now may be accessed only using that address. However, on heavy loaded systems, time between first and second musb ep0 interrupts may be too long and musb controller misses requests between. As result, device enumeration may be unsuccessful. This can be checked on USB3.0 Host and using USB3.0 test suite (from usb.org) running ch9 tests for USB2.0 devices. Usually 'Addressed state/TD9.1: Device Descriptor Test' will fail The fix consists in checking CSR0L.DataEnd state and assigning the device address in the first ep0 interrupt handling, so delay is as minimal as possible Signed-off-by: Ruslan Bilovol --- drivers/usb/musb/musb_gadget_ep0.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/drivers/usb/musb/musb_gadget_ep0.c b/drivers/usb/musb/musb_gadget_ep0.c index c9c1ac4..59bc5a5 100644 --- a/drivers/usb/musb/musb_gadget_ep0.c +++ b/drivers/usb/musb/musb_gadget_ep0.c @@ -885,6 +885,37 @@ stall: finish: musb_writew(regs, MUSB_CSR0, musb->ackpend); + + /* + * If we are at end of SET_ADDRESS sequence, + * update the address immediately if possible, + * otherwise we may miss packets between + * sending ACK from musb side and musb's next + * interrupt handler firing (in which we update + * the address). At least this fixes next + * USB2.0 ch9 test of USB30CV utility: + * "Addressed state - Device Descriptor test" + */ + if (musb->set_address && (musb->ackpend & + MUSB_CSR0_P_DATAEND) && + (musb->ep0_state == + MUSB_EP0_STAGE_STATUSIN)) { + u16 ack_delay = 500; + + while ((musb_readw(regs, MUSB_CSR0) & + MUSB_CSR0_P_DATAEND) && + --ack_delay) { + cpu_relax(); + udelay(1); + } + + if (ack_delay) { + musb->set_address = false; + musb_writeb(mbase, MUSB_FADDR, + musb->address); + } + } + musb->ackpend = 0; } } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/