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[23.128.96.18]) by mx.google.com with ESMTP id i6si3252312ejs.300.2020.11.11.17.38.17; Wed, 11 Nov 2020 17:38:41 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@fnarfbargle.com header.s=mail header.b=iLRvYT1I; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=fnarfbargle.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728958AbgKLBgD (ORCPT + 99 others); Wed, 11 Nov 2020 20:36:03 -0500 Received: from ns3.fnarfbargle.com ([103.4.19.87]:54336 "EHLO ns3.fnarfbargle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727925AbgKKXa7 (ORCPT ); Wed, 11 Nov 2020 18:30:59 -0500 Received: from srv.home ([10.8.0.1] ident=heh4648) by ns3.fnarfbargle.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84_2) (envelope-from ) id 1kczXn-00057Q-J0; Thu, 12 Nov 2020 07:28:51 +0800 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=fnarfbargle.com; s=mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:References:Cc:To:Subject:From; bh=aDZuAoa5pHuOQbtSVm+Q62xoeuPrqmcgO4MplIKPrUA=; b=iLRvYT1IO4cvaDXMLUgjDx/6OnwR+uLCmN8f7ZhB5B1R8hhJRWoSU5ezjPEqZXIAQVtzYU9uO9LL7kSj3sbMMmtIUv/N0oHpBsR0pOkZ3CIjNHMZt9fRdiqFuMBk53PXRsCO9LuL+eu5RECXuHFlpQLePtGV2BIhy/PP0eYvunQ=; From: Brad Campbell Subject: Re: [PATCH v5 1/1] applesmc: Re-work SMC comms To: Henrik Rydberg , linux-hwmon@vger.kernel.org Cc: Arnd Bergmann , "linux-kernel@vger.kernel.org" , hns@goldelico.com, Andreas Kemnade , Jean Delvare , Guenter Roeck References: <20200930105442.3f642f6c@aktux> <20201104142057.62493c12@aktux> <2436afef-99c6-c352-936d-567bf553388c@fnarfbargle.com> <7a085650-2399-08c0-3c4d-6cd1fa28a365@roeck-us.net> <10027199-5d31-93e7-9bd8-7baaebff8b71@roeck-us.net> <70331f82-35a1-50bd-685d-0b06061dd213@fnarfbargle.com> <3c72ccc3-4de1-b5d0-423d-7b8c80991254@fnarfbargle.com> <6d071547-10ee-ca92-ec8b-4b5069d04501@bitmath.org> <8e117844-d62a-bcb1-398d-c59cc0d4b878@fnarfbargle.com> <9109d059-d9cb-7464-edba-3f42aa78ce92@bitmath.org> <5310c0ab-0f80-1f9e-8807-066223edae13@bitmath.org> <57057d07-d3a0-8713-8365-7b12ca222bae@fnarfbargle.com> <4eca09dc-7b32-767c-eab0-b9ad8b41efcc@fnarfbargle.com> <8c525b3b-b4a6-8ee4-8128-a20e0ad408e4@fnarfbargle.com> <29b03865-f00a-f121-b7a5-c4b9179a27cb@bitmath.org> Message-ID: Date: Thu, 12 Nov 2020 10:28:50 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.2.2 MIME-Version: 1.0 In-Reply-To: <29b03865-f00a-f121-b7a5-c4b9179a27cb@bitmath.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/11/20 7:05 am, Henrik Rydberg wrote: > On 2020-11-11 14:06, Brad Campbell wrote: >> Commit fff2d0f701e6 ("hwmon: (applesmc) avoid overlong udelay()") >> introduced an issue whereby communication with the SMC became >> unreliable with write errors like : >> >> [  120.378614] applesmc: send_byte(0x00, 0x0300) fail: 0x40 >> [  120.378621] applesmc: LKSB: write data fail >> [  120.512782] applesmc: send_byte(0x00, 0x0300) fail: 0x40 >> [  120.512787] applesmc: LKSB: write data fail >> >> The original code appeared to be timing sensitive and was not reliable >> with the timing changes in the aforementioned commit. >> >> This patch re-factors the SMC communication to remove the timing >> dependencies and restore function with the changes previously >> committed. Logic changes based on inspection of the Apple SMC kext. >> >> Tested on : MacbookAir6,2 MacBookPro11,1 iMac12,2, MacBookAir1,1, >> MacBookAir3,1 >> >> Fixes: fff2d0f701e6 ("hwmon: (applesmc) avoid overlong udelay()") >> Reported-by: Andreas Kemnade >> Tested-by: Andreas Kemnade # MacBookAir6,2 >> Acked-by: Arnd Bergmann >> Signed-off-by: Brad Campbell >> Signed-off-by: Henrik Rydberg >> >> --- >> Changelog : >> v1 : Initial attempt >> v2 : Address logic and coding style >> v3 : Removed some debug hangover. Added tested-by. Modifications for MacBookAir1,1 >> v4 : Re-factored logic based on Apple driver. Simplified wait_status loop >> v5 : Re-wrote status loop. Simplified busy check in send_byte(). Fixed formatting > > Hi Brad, > > This version is still working fine on the MBA1,1, at 50 reads per second. > Cheers Henrik, I did 5.6 million reads overnight and had 3 failures. I suspect it's this : status = inb(APPLESMC_CMD_PORT) & SMC_STATUS_BUSY; if (!status) return -EIO; When I used wait_status() previously I didn't see any read errors. With hindsight I probably shouldn't have made that simplification. I'll do some more testing and probably submit a v6 with just this change. I think it's just about right provided that wait_status loop gets across the line. Regards, Brad