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 52A05C433FE for ; Mon, 18 Oct 2021 12:27:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3937C60F56 for ; Mon, 18 Oct 2021 12:27:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231495AbhJRM3x (ORCPT ); Mon, 18 Oct 2021 08:29:53 -0400 Received: from m43-7.mailgun.net ([69.72.43.7]:47938 "EHLO m43-7.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229843AbhJRM3w (ORCPT ); Mon, 18 Oct 2021 08:29:52 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1634560061; h=Date: Message-ID: Cc: To: References: In-Reply-To: From: Subject: Content-Transfer-Encoding: MIME-Version: Content-Type: Sender; bh=RnKubHLBxsURiKk2HojMzMbLeWSvD8hkXWqctYdrYCU=; b=teQlPUV79NuU3t20Icdz6fME80ajitnbTNYHewUfd+uBJsKGgwP18i7jpfZwXF+5WGanXWPx JPUVscNZLbmhJX7h35j3yIW4qdRETlWaKlouiVW/WpfyX6KzfCLl4gi1be2hID6C+VLF+GKY eh0hUQ6vc8VeMfjxl35CZcaruxA= X-Mailgun-Sending-Ip: 69.72.43.7 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n05.prod.us-east-1.postgun.com with SMTP id 616d682cab9da96e64d7dbc7 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Mon, 18 Oct 2021 12:27:24 GMT Sender: kvalo=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 3B46AC43617; Mon, 18 Oct 2021 12:27:24 +0000 (UTC) Received: from tykki.adurom.net (tynnyri.adurom.net [51.15.11.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: kvalo) by smtp.codeaurora.org (Postfix) with ESMTPSA id D3172C4338F; Mon, 18 Oct 2021 12:27:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 smtp.codeaurora.org D3172C4338F Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=codeaurora.org Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: Re: [PATCH] mwifiex: Add quirk resetting the PCI bridge on MS Surface devices From: Kalle Valo In-Reply-To: <20211011134238.16551-1-verdre@v0yd.nl> References: <20211011134238.16551-1-verdre@v0yd.nl> To: =?utf-8?q?Jonas_Dre=C3=9Fler?= Cc: Amitkumar Karwar , Ganapathi Bhat , Xinming Hu , "David S. Miller" , Jakub Kicinski , =?utf-8?q?Jonas_Dre=C3=9Fler?= , Tsuchiya Yuto , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Maximilian Luz , Andy Shevchenko , Bjorn Helgaas , =?utf-8?q?Pali_Roh=C3=A1r?= , Heiner Kallweit , Johannes Berg , Brian Norris , David Laight User-Agent: pwcli/0.1.0-git (https://github.com/kvalo/pwcli/) Python/3.7.3 Message-ID: <163456003528.19217.10035499117616642207.kvalo@codeaurora.org> Date: Mon, 18 Oct 2021 12:27:24 +0000 (UTC) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jonas Dreßler wrote: > The most recent firmware (15.68.19.p21) of the 88W8897 PCIe+USB card > reports a hardcoded LTR value to the system during initialization, > probably as an (unsuccessful) attempt of the developers to fix firmware > crashes. This LTR value prevents most of the Microsoft Surface devices > from entering deep powersaving states (either platform C-State 10 or > S0ix state), because the exit latency of that state would be higher than > what the card can tolerate. > > Turns out the card works just the same (including the firmware crashes) > no matter if that hardcoded LTR value is reported or not, so it's kind > of useless and only prevents us from saving power. > > To get rid of those hardcoded LTR requirements, it's possible to reset > the PCI bridge device after initializing the cards firmware. I'm not > exactly sure why that works, maybe the power management subsystem of the > PCH resets its stored LTR values when doing a function level reset of > the bridge device. Doing the reset once after starting the wifi firmware > works very well, probably because the firmware only reports that LTR > value a single time during firmware startup. > > Signed-off-by: Jonas Dreßler I'm not sure what was the conclusion from the discussion, so dropping the patch. Please resend once it's ready to be applied. Patch set to Changes Requested. -- https://patchwork.kernel.org/project/linux-wireless/patch/20211011134238.16551-1-verdre@v0yd.nl/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches