From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752921Ab3LQX4H (ORCPT ); Tue, 17 Dec 2013 18:56:07 -0500 Received: from seketeli.net ([91.121.166.71]:35488 "EHLO ms.seketeli.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751990Ab3LQX4D (ORCPT ); Tue, 17 Dec 2013 18:56:03 -0500 From: Apelete Seketeli To: linux-usb@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Felipe Balbi , Lars-Peter Clausen Subject: [PATCH v2 3/3] usb: musb: fix setting JZ4740 gadget periphal mode on reset Date: Wed, 18 Dec 2013 00:56:01 +0100 Message-Id: <1387324561-21578-4-git-send-email-apelete@seketeli.net> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1387324561-21578-1-git-send-email-apelete@seketeli.net> References: <1387324561-21578-1-git-send-email-apelete@seketeli.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org JZ4740 USB Device Controller is not OTG compatible and does not have DEVCTL register in silicon. During ethernet-over-usb transactions, on reset, musb driver tries to read from DEVCTL and consequently sets device as host (A-Device) instead of peripheral (B-Device), which makes it a composite device to the USB gadget driver. This induces a kernel panic during power down where the USB gadget driver does a null pointer dereference when trying to access the composite device configuration. On reset, do not rely on DEVCTL value for setting gadget peripheral mode. Use is_otg flag instead to set it to B-Device. Signed-off-by: Apelete Seketeli --- drivers/usb/musb/musb_gadget.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c index 32fb057..cb50163 100644 --- a/drivers/usb/musb/musb_gadget.c +++ b/drivers/usb/musb/musb_gadget.c @@ -2119,7 +2119,15 @@ __acquires(musb->lock) /* Normal reset, as B-Device; * or else after HNP, as A-Device */ - if (devctl & MUSB_DEVCTL_BDEVICE) { + if (!musb->g.is_otg) { + /* USB device controllers that are not OTG compatible + * may not have DEVCTL register in silicon. + * In that case, do not rely on devctl for setting + * peripheral mode. + */ + musb->xceiv->state = OTG_STATE_B_PERIPHERAL; + musb->g.is_a_peripheral = 0; + } else if (devctl & MUSB_DEVCTL_BDEVICE) { musb->xceiv->state = OTG_STATE_B_PERIPHERAL; musb->g.is_a_peripheral = 0; } else { -- 1.7.10.4