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=-17.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_2 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 CFEF7C433EF for ; Thu, 9 Sep 2021 13:27:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AC80C611CB for ; Thu, 9 Sep 2021 13:27:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355391AbhIIN24 (ORCPT ); Thu, 9 Sep 2021 09:28:56 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:54084 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356944AbhIINPA (ORCPT ); Thu, 9 Sep 2021 09:15:00 -0400 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 938501FDEE; Thu, 9 Sep 2021 13:13:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1631193227; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pFMRfoyR43hfi0VWujmUi6zgOxK+wVXStaOWAPl9ihk=; b=jwKuuIPjmKLoBl9qRZBKB49VW4UfAudv/rGnMyjKgBqPkpmrFqAOXvMM1+HsncTPIFyjLG UiDZJT/R9vrZyXHupExniDumvyGKGJvCfCBpsa80aGmMpDEj3K4weQaS47ndkZeu/EiaZN TRUZCzHzOZZcl2h+4MwOhVbdwy0qYR8= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1631193227; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pFMRfoyR43hfi0VWujmUi6zgOxK+wVXStaOWAPl9ihk=; b=baFrK6w72S8VISeLlLZ1TZebCQin7lJIg4i8J+4B6Hlg2+qdOH9YOKCCx4rUfiZHL1MTLm pR13G4mWYUcgyqCw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 3A5B513B36; Thu, 9 Sep 2021 13:13:47 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id KFuqC4sIOmFKDwAAMHmgww (envelope-from ); Thu, 09 Sep 2021 13:13:47 +0000 Date: Thu, 9 Sep 2021 15:13:20 +0200 From: Jean Delvare To: Sasha Levin Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Heiner Kallweit , Wolfram Sang , linux-i2c@vger.kernel.org Subject: Re: [PATCH AUTOSEL 5.14 088/252] i2c: i801: Fix handling SMBHSTCNT_PEC_EN Message-ID: <20210909151320.7bddd134@endymion> In-Reply-To: <20210909114106.141462-88-sashal@kernel.org> References: <20210909114106.141462-1-sashal@kernel.org> <20210909114106.141462-88-sashal@kernel.org> Organization: SUSE Linux X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.32; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sascha, On Thu, 9 Sep 2021 07:38:22 -0400, Sasha Levin wrote: > From: Heiner Kallweit > > [ Upstream commit a6b8bb6a813a6621c75ceacd1fa604c0229e9624 ] > > Bit SMBHSTCNT_PEC_EN is used only if software calculates the CRC and > uses register SMBPEC. This is not supported by the driver, it supports > hw-calculation of CRC only (using bit SMBAUXSTS_CRCE). The chip spec > states the following, therefore never set bit SMBHSTCNT_PEC_EN. > > Chapter SMBus CRC Generation and Checking > If the AAC bit is set in the Auxiliary Control register, the PCH > automatically calculates and drives CRC at the end of the transmitted > packet for write cycles, and will check the CRC for read cycles. It will > not transmit the contents of the PEC register for CRC. The PEC bit must > not be set in the Host Control register. If this bit is set, unspecified > behavior will result. > > This patch is based solely on the specification and compile-tested only, > because I have no PEC-capable devices. > > Signed-off-by: Heiner Kallweit > Tested-by: Jean Delvare > Signed-off-by: Wolfram Sang > Signed-off-by: Sasha Levin > --- > drivers/i2c/busses/i2c-i801.c | 27 +++++++++++---------------- > 1 file changed, 11 insertions(+), 16 deletions(-) This patch fixes a theoretical problem nobody has ever complained about. I don't think it makes sense to backport it to stable kernel branches. -- Jean Delvare SUSE L3 Support