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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07A38C433F5 for ; Thu, 30 Sep 2021 15:42:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFC00615E5 for ; Thu, 30 Sep 2021 15:42:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345681AbhI3Pnt (ORCPT ); Thu, 30 Sep 2021 11:43:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:59744 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345133AbhI3Pns (ORCPT ); Thu, 30 Sep 2021 11:43:48 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6903E61361; Thu, 30 Sep 2021 15:42:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633016525; bh=Ld6gmKgj4ZkpFLxu/49x5Bat/dDZqy1PdYTRqKMcEmA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jlXDpf2+6u93jQCh2igjEF8goUz2IeBzFfBCaMWtFFxkZjzaF6vMhu5iyclcS2D9v HgWr48obLMbc1RwdspGfSjMZwkf1KYlYnCjo/JsLTD3Bi5Cm++W0LfBVdB8ro8mCU9 kSM4wFHPbJnX7jdweMj71nqIa7JClCr0nmAoNJBAlqwfpKpG6uEBhUA3hieCETQpQ+ Nb2qg3A+Lh9vp3M5KF4NBR6SvhMRuP3mpfj7ca7qXSqiEM0BJTOZgixsB/pWrJV8KL 7pEmG1CMnW/2Yy1Axg8lY3ZaSUmjZ7pL+4wslkhFveEPYTCenBKtBrwgVFOEAYcumK rRe9dhWEx714w== Received: by pali.im (Postfix) id E29DEE79; Thu, 30 Sep 2021 17:42:02 +0200 (CEST) Date: Thu, 30 Sep 2021 17:42:02 +0200 From: Pali =?utf-8?B?Um9ow6Fy?= To: Jonas =?utf-8?Q?Dre=C3=9Fler?= Cc: Andy Shevchenko , Brian Norris , Amitkumar Karwar , Ganapathi Bhat , Xinming Hu , Kalle Valo , "David S. Miller" , Jakub Kicinski , Tsuchiya Yuto , linux-wireless , netdev@vger.kernel.org, Linux Kernel , linux-pci , Maximilian Luz , Andy Shevchenko , Bjorn Helgaas Subject: Re: [PATCH 1/2] mwifiex: Use non-posted PCI register writes Message-ID: <20210930154202.cvw3it3edv7pmqtb@pali> References: <0ce93e7c-b041-d322-90cd-40ff5e0e8ef0@v0yd.nl> <20210923202231.t2zjoejpxrbbe5hc@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: NeoMutt/20180716 Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Thursday 30 September 2021 17:38:43 Jonas Dreßler wrote: > On 9/23/21 10:22 PM, Pali Rohár wrote: > > On Thursday 23 September 2021 22:41:30 Andy Shevchenko wrote: > > > On Thu, Sep 23, 2021 at 6:28 PM Jonas Dreßler wrote: > > > > On 9/22/21 2:50 PM, Jonas Dreßler wrote: > > > > > > ... > > > > > > > - Just calling mwifiex_write_reg() once and then blocking until the card > > > > wakes up using my delay-loop doesn't fix the issue, it's actually > > > > writing multiple times that fixes the issue > > > > > > > > These observations sound a lot like writes (and even reads) are actually > > > > being dropped, don't they? > > > > > > It sounds like you're writing into a not ready (fully powered on) device. > > > > This reminds me a discussion with Bjorn about CRS response returned > > after firmware crash / reset when device is not ready yet: > > https://lore.kernel.org/linux-pci/20210922164803.GA203171@bhelgaas/ > > > > Could not be this similar issue? You could check it via reading > > PCI_VENDOR_ID register from config space. And if it is not valid value > > then card is not really ready yet. > > > > > To check this, try to put a busy loop for reading and check the value > > > till it gets 0. > > > > > > Something like > > > > > > unsigned int count = 1000; > > > > > > do { > > > if (mwifiex_read_reg(...) == 0) > > > break; > > > } while (--count); > > > > > > > > > -- > > > With Best Regards, > > > Andy Shevchenko > > I've tried both reading PCI_VENDOR_ID and the firmware status using a busy > loop now, but sadly none of them worked. It looks like the card always > replies with the correct values even though it sometimes won't wake up after > that. > > I do have one new observation though, although I've no clue what could be > happening here: When reading PCI_VENDOR_ID 1000 times to wakeup we can > "predict" the wakeup failure because exactly one (usually around the 20th) > of those 1000 reads will fail. What does "fail" means here? > Maybe the firmware actually tries to wake up, > encounters an error somewhere in its wakeup routines and then goes down a > special failure code path. That code path keeps the cards CPU so busy that > at some point a PCI_VENDOR_ID request times out? > > Or well, maybe the card actually wakes up fine, but we don't receive the > interrupt on our end, so many possibilities...