Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161672AbbKSVMg (ORCPT ); Thu, 19 Nov 2015 16:12:36 -0500 Received: from mail-yk0-f182.google.com ([209.85.160.182]:36765 "EHLO mail-yk0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934471AbbKSVMe convert rfc822-to-8bit (ORCPT ); Thu, 19 Nov 2015 16:12:34 -0500 MIME-Version: 1.0 In-Reply-To: References: <1447962313-17069-1-git-send-email-dianders@chromium.org> <1447962313-17069-2-git-send-email-dianders@chromium.org> Date: Thu, 19 Nov 2015 13:12:33 -0800 X-Google-Sender-Auth: U_NyNaL_qrqEH9O56aVpqDGjJzQ Message-ID: Subject: Re: [PATCH v3 2/2] usb: dwc2: host: Clear interrupts before handling them From: Doug Anderson To: =?UTF-8?B?QW50dGkgU2VwcMOkbMOk?= Cc: John Youn , Felipe Balbi , Yunzhi Li , =?UTF-8?Q?Heiko_St=C3=BCbner?= , "open list:ARM/Rockchip SoC..." , Julius Werner , "Herrero, Gregory" , "Kaukab, Yousaf" , Dinh Nguyen , John Youn , Greg Kroah-Hartman , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2335 Lines: 62 Antti, On Thu, Nov 19, 2015 at 1:09 PM, Antti Seppälä wrote: > On 19 November 2015 at 21:45, Douglas Anderson wrote: >> In general it is wise to clear interrupts before processing them. If >> you don't do that, you can get: >> 1. Interrupt happens >> 2. You look at system state and process interrupt >> 3. A new interrupt happens >> 4. You clear interrupt without processing it. >> >> This patch was actually a first attempt to fix missing device insertions >> as described in (usb: dwc2: host: Fix missing device insertions) and it >> did solve some of the signal bouncing problems but not all of >> them (which is why I submitted the other patch). Specifically, this >> patch itself would sometimes change: >> 1. hardware sees connect >> 2. hardware sees disconnect >> 3. hardware sees connect >> 4. dwc2_port_intr() - clears connect interrupt >> 5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect() >> >> ...to: >> 1. hardware sees connect >> 2. hardware sees disconnect >> 3. dwc2_port_intr() - clears connect interrupt >> 4. hardware sees connect >> 5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect() >> >> ...but with different timing then sometimes we'd still miss cable >> insertions. >> >> In any case, though this patch doesn't fix any (known) problems, it >> still seems wise as a general policy to clear interrupt before handling >> them. >> >> Signed-off-by: Douglas Anderson >> Acked-by: John Youn >> Tested-by: John Youn >> --- >> Changes in v3: >> - Don't (uselessly) clear the PRTINT anymore (Felipe Balbi). >> >> Changes in v2: None >> > > Hi. > > It seems that towards the end of hcd_intr.c you seem to be switching a > few calls of dwc2_writel() to plain writel(). It looks like something > that is easily overlooked but please always use dwc2_writel to > preserve correct register endianness on big-endian platforms. Oops! That was a very dumb oversight, thanks for catching. Sorry about that. Fix coming. -Doug -- 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/