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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 25552C43216 for ; Wed, 1 Sep 2021 14:02:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0DB0B6102A for ; Wed, 1 Sep 2021 14:02:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244684AbhIAODA (ORCPT ); Wed, 1 Sep 2021 10:03:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240837AbhIAODA (ORCPT ); Wed, 1 Sep 2021 10:03:00 -0400 Received: from mout-p-102.mailbox.org (mout-p-102.mailbox.org [IPv6:2001:67c:2050::465:102]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 278AEC061575; Wed, 1 Sep 2021 07:02:03 -0700 (PDT) Received: from smtp102.mailbox.org (smtp102.mailbox.org [80.241.60.233]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-102.mailbox.org (Postfix) with ESMTPS id 4H05Ms116kzQkF0; Wed, 1 Sep 2021 16:02:01 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Subject: Re: [PATCH 1/2] mwifiex: Use non-posted PCI register writes To: Andy Shevchenko Cc: Amitkumar Karwar , Ganapathi Bhat , Xinming Hu , Kalle Valo , "David S. Miller" , Jakub Kicinski , Tsuchiya Yuto , "open list:TI WILINK WIRELES..." , netdev , Linux Kernel Mailing List , linux-pci , Maximilian Luz , Andy Shevchenko , Bjorn Helgaas , =?UTF-8?Q?Pali_Roh=c3=a1r?= References: <20210830123704.221494-1-verdre@v0yd.nl> <20210830123704.221494-2-verdre@v0yd.nl> From: =?UTF-8?Q?Jonas_Dre=c3=9fler?= Message-ID: <7e38931e-2f1c-066e-088e-b27b56c1245c@v0yd.nl> Date: Wed, 1 Sep 2021 16:01:54 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: CEE9126D Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On 8/30/21 2:49 PM, Andy Shevchenko wrote: > On Mon, Aug 30, 2021 at 3:38 PM Jonas Dreßler wrote: >> >> On the 88W8897 card it's very important the TX ring write pointer is >> updated correctly to its new value before setting the TX ready >> interrupt, otherwise the firmware appears to crash (probably because >> it's trying to DMA-read from the wrong place). >> >> Since PCI uses "posted writes" when writing to a register, it's not >> guaranteed that a write will happen immediately. That means the pointer >> might be outdated when setting the TX ready interrupt, leading to >> firmware crashes especially when ASPM L1 and L1 substates are enabled >> (because of the higher link latency, the write will probably take >> longer). >> >> So fix those firmware crashes by always forcing non-posted writes. We do >> that by simply reading back the register after writing it, just as a lot >> of other drivers do. >> >> There are two reproducers that are fixed with this patch: >> >> 1) During rx/tx traffic and with ASPM L1 substates enabled (the enabled >> substates are platform dependent), the firmware crashes and eventually a >> command timeout appears in the logs. That crash is fixed by using a >> non-posted write in mwifiex_pcie_send_data(). >> >> 2) When sending lots of commands to the card, waking it up from sleep in >> very quick intervals, the firmware eventually crashes. That crash >> appears to be fixed by some other non-posted write included here. > > Thanks for all this work! > > Nevertheless, do we have any commits that may be a good candidate to > be in the Fixes tag here? > I don't think there's any commit we could point to, given that the bug is probably somewhere in the firmware code. >> Signed-off-by: Jonas Dreßler >> --- >> drivers/net/wireless/marvell/mwifiex/pcie.c | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/drivers/net/wireless/marvell/mwifiex/pcie.c b/drivers/net/wireless/marvell/mwifiex/pcie.c >> index c6ccce426b49..bfd6e135ed99 100644 >> --- a/drivers/net/wireless/marvell/mwifiex/pcie.c >> +++ b/drivers/net/wireless/marvell/mwifiex/pcie.c >> @@ -237,6 +237,12 @@ static int mwifiex_write_reg(struct mwifiex_adapter *adapter, int reg, u32 data) >> >> iowrite32(data, card->pci_mmap1 + reg); >> >> + /* Do a read-back, which makes the write non-posted, ensuring the >> + * completion before returning. > >> + * The firmware of the 88W8897 card is buggy and this avoids crashes. > > Any firmware version reference? Would be nice to have just for the > sake of record. > Pretty sure the crash is present in every firmware that has been released, I've tried most of them. FTR, the current firmware version is 15.68.19.p21. >> + */ >> + ioread32(card->pci_mmap1 + reg); >> + >> return 0; >> } > >