From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9968ECA9EAF for ; Wed, 30 Oct 2019 06:28:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6A8ED2067D for ; Wed, 30 Oct 2019 06:28:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="Pqe9OmYj"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="aAV3QxGb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727119AbfJ3G2p (ORCPT ); Wed, 30 Oct 2019 02:28:45 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:56158 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726108AbfJ3G2p (ORCPT ); Wed, 30 Oct 2019 02:28:45 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id CB0AA60E75; Wed, 30 Oct 2019 06:28:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1572416924; bh=3EtR8jh7t7c6zO5KJFSNoxdrq9KxP2FUsVIMb+Yz9uc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Pqe9OmYj9dfyln7Jp8Z9c/SlgYDgDZGo/mBLESPRJ/LB1qCUw86SYHrt+GGckzNiB i9VX7s9QZKqhlJOVbUXChb9C60z4RtcUydytRoiIBRWb8ESbOrLD6pAXOcRz087M3V OiChyuCNL9OBnMwwrRSqvOBPCrXo4tx8p01puPOw= Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id AF3DE60610; Wed, 30 Oct 2019 06:28:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1572416921; bh=3EtR8jh7t7c6zO5KJFSNoxdrq9KxP2FUsVIMb+Yz9uc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=aAV3QxGbeXqzA+vpyBpDIszwnFDyFYb56JNgs1eiAaU8TLy9lj1f3LIhMBSpcKHbh TZ2JEeURLzv6rhRtI63zjY2RNWaytxqDZI1ehwN/6RV2/Bz2VxmZifhyDmW7S5c0E4 9GNYx1bmiKjrbWiYYp8aflw4wUppuACnTkd84T3U= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 30 Oct 2019 14:28:41 +0800 From: zhichen@codeaurora.org To: Adrian Chadd Cc: Peter Oh , ath10k , linux-wireless@vger.kernel.org Subject: Re: [PATCH RFC] Revert "ath10k: fix DMA related firmware crashes on multiple devices" In-Reply-To: References: <1571734629-18028-1-git-send-email-zhichen@codeaurora.org> Message-ID: X-Sender: zhichen@codeaurora.org User-Agent: Roundcube Webmail/1.2.5 Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On 2019-10-23 02:24, Adrian Chadd wrote: > On Tue, 22 Oct 2019 at 10:17, Peter Oh wrote: >> >> >> On 10/22/19 1:57 AM, Zhi Chen wrote: >> > This reverts commit 76d164f582150fd0259ec0fcbc485470bcd8033e. >> > PCIe hung issue was observed on multiple platforms. The issue was reproduced >> > when DUT was configured as AP and associated with 50+ STAs. >> > >> > With PCIe protocol analyzer, we can see DMA Read crossing 4KB boundary when >> > issue happened. It broke PCIe spec and caused PCIe stuck. >> >> How can you say value 0 (I believe it's 64 bytes) DMA burst size >> causes >> the symptom and 1 fixes it? > > > +1 to this question. > > Also, shouldn't the DMA engine be doing what the firmware says? Is the > firmware/copy engine actually somehow bursting / prefetching across a > 4K page boundary? > > Surely this is something that can be fixed in software/firmware by > correctly configuring up buffer size/offsets? > > > > -Adrian DMA engine is working as expected as the configuration. It's copy engine which actually splits the RD/WR requests and accesses host memory. And yes it's platform related configuration. We have never hit this issue on x86 platform. Zhi