Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162731AbbKTQtT (ORCPT ); Fri, 20 Nov 2015 11:49:19 -0500 Received: from mail-yk0-f173.google.com ([209.85.160.173]:34941 "EHLO mail-yk0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759651AbbKTQtR (ORCPT ); Fri, 20 Nov 2015 11:49:17 -0500 MIME-Version: 1.0 In-Reply-To: <87y4dsd6hr.fsf@saruman.tx.rr.com> References: <1447968195-32097-1-git-send-email-dianders@chromium.org> <1447968195-32097-2-git-send-email-dianders@chromium.org> <87y4dsd6hr.fsf@saruman.tx.rr.com> Date: Fri, 20 Nov 2015 08:49:15 -0800 X-Google-Sender-Auth: v_8x0t5zjDy7ZsRcxPwvhK4s2jA Message-ID: Subject: Re: [PATCH v4 2/2] usb: dwc2: host: Clear interrupts before handling them From: Doug Anderson To: Felipe Balbi Cc: John Youn , 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 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2793 Lines: 74 Felipe, On Fri, Nov 20, 2015 at 7:40 AM, Felipe Balbi wrote: > > Hi, > > Douglas Anderson writes: >> 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. >> >> Note that for dwc2_handle_usb_port_intr(), instead of moving the clear >> of PRTINT to the beginning of the function we remove it completely. The >> only way to clear PRTINT is to clear the sources that set it in the >> first place. >> >> Signed-off-by: Douglas Anderson >> Acked-by: John Youn >> Tested-by: John Youn > > $ patch -p1 --dry-run < patch.diff > checking file drivers/usb/dwc2/core_intr.c > checking file drivers/usb/dwc2/hcd_intr.c > Hunk #4 FAILED at 365. > Hunk #5 succeeded at 388 (offset 11 lines). > 1 out of 5 hunks FAILED > > Care to rebase on top of my testing/next ? No problem. ...though when I did that, I actually found (by code inspection) a bug in the original patch, so I guess it's a good thing it didn't apply... ...and then that led me to another bug that was pre-existing. I'll send up two new patches shortly. I'll remove John's Ack and Tested tags from the patch since it contains a change. It looks like you already landed part 1 of this series (usb: dwc2: host: Fix missing device insertions) so I won't resend that. -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/