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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CF459C5DF7D for ; Fri, 21 Aug 2026 09:08:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=aGEJQB9358mwZctsDDONapSyTxRcKMMADgC4+MXroNA=; b=Dhy8I0F76+aGyn/FRsehvouhPh +/3DzHThd4a6aZbt7YJZUNXlu96tFW6n8cMPCO/wgBZwKOkZBhIGscB8WJpciiZ5F0qbY4zfEjVCX XUB8yNpWYH3PBw91jSRGo7D9bAiJUNMnlPrwjG64/3bc05gFRRrdS0BXfm9jTynC+yhhy0vDUA6M6 GdRIay1sbftSPiGNyKYY0lDwmpr5l0Y5/Epba2uULc/rW5p9O4INStiweI+t9AlFOQmq0B6m7uHXM 73n+rWsIGfQYw6On8b+UySdeeBiZgnFN1CifzEMSQ1cxdVaobmLc3OkQ3MpQsuO8wExg/PzNSPFLe 8t9YTgLQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wxLEO-0000000CtQ5-2stP; Fri, 21 Aug 2026 09:08:08 +0000 Received: from submarine.notk.org ([62.210.214.84]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wxLEL-0000000CtP4-1PgA for linux-arm-kernel@lists.infradead.org; Fri, 21 Aug 2026 09:08:07 +0000 Received: from gaia.codewreck.org (localhost [127.0.0.1]) by submarine.notk.org (Postfix) with ESMTPS id 8F07A14C2D6; Fri, 21 Aug 2026 11:07:52 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codewreck.org; s=2; t=1787303277; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=aGEJQB9358mwZctsDDONapSyTxRcKMMADgC4+MXroNA=; b=M2jn6TbVDXHVkr/DG2auw74KFiKThPfC0XasZSWIF0/2H3vkffPYarZ0Z189yUSvAFBHf/ QbLJi8iGq8/DbVwhhl3Z+c5DH2i0qrzOvtU7quhd+lgDZveIW05P/3uIoPAptls8dYDr5E oOqeQZU7+rq3031TM9LrHcMu2FRVn0CvkLU0PheUnT6lGAg/RscCEnLnNWAqzpZxFkv8i6 5ZstEmf9todvM8Gtz1f3DPH91+qfKMcPuALJTE2R6K3FFDITuuY7Uc+ft9D1qhN2Dv4z9V u4S8i4qdypfe+OQdqztFxRKI9jUWypUnpz5o+4p92UwGFectm2NXZQS42rRXrw== Received: from localhost (gaia.codewreck.org [local]) by gaia.codewreck.org (OpenSMTPD) with ESMTPA id 622dfed3; Fri, 21 Aug 2026 09:07:50 +0000 (UTC) Date: Fri, 21 Aug 2026 18:07:35 +0900 From: Dominique Martinet To: Vincent Jardin Cc: Oleksij Rempel , Pengutronix Kernel Team , Andi Shyti , Frank Li , Sascha Hauer , Fabio Estevam , Wolfram Sang , Kaushal Butala , Shawn Guo , Stefan Eichenberger , linux-i2c@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Carlos Song , Stefan Eichenberger Subject: Re: [PATCH v3 0/2] i2c: imx: fix SMBus block-read of 0 locking the bus [stable backport question/offer] Message-ID: References: <20260713-for-upstream-i2c-lx2160-fix-v1-v3-0-073ac9e103a5@free.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260713-for-upstream-i2c-lx2160-fix-v1-v3-0-073ac9e103a5@free.fr> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260821_020805_788591_8EFB69E7 X-CRM114-Status: GOOD ( 15.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Vincent Jardin wrote on Mon, Jul 13, 2026 at 08:11:58PM +0200: > i2c-imx rejects an SMBus Block Read byte count of 0 (valid per SMBus 3.1 > 6.5.7) as -EPROTO and returns without emitting a NACK + STOP, leaving the > target holding SDA so the bus stays stuck until a power cycle. > > It was triggered by an MPQ8785 PMBus regulator on a LX2160A i2c > bus: when the kernel binds it using the pmbus/hwmon framework, the bus > locks up and it does never recovers. It was confirmed with a scope, with > and without the fix. > > The same bug is occuring with two independently introduced spots, so the > fix is two patches with their respective Fixes: tags and backport ranges > > 1/2 atomic/polling path Fixes: 8e8782c71595 v3.16+ > 2/2 IRQ-driven state machine Fixes: 5f5c2d4579ca v6.13+ Silly question (half for stable people, half for i2c-imx maintainers), but the backport for commit cb2fc3785769 ("i2c: imx: fix locked bus on SMBus block-read of 0 (atomic)") to stable brought in b460b15b3cc2 ("i2c: imx: separate atomic, dma and non-dma use case") (also 6.13+) as a dep (all the way back to 5.10!); with that commit in, 5f5c2d4579ca ("i2c: imx: prevent rescheduling in non dma mode") applies almost cleanly on 6.6/6.12[1]... So should we grab more easy fixes? In particular, I doubt I'll ever hit this SMBus 3.1 bug, but 5f5c2d4579ca also was a real fix[2], so would it make sense to jump in and get both 5f5c2d4579ca and 07fd9385f0d8 ("i2c: imx: fix locked bus on SMBus block-read of 0 (IRQ)") for 6.6/6.12? [1] just a trivial context conflict in the struct there, but it starts being more iffy on 6.1 and earlier kernels [2] ... We actually ran into that bug on 5.10, our kludgy backport being the reason I noticed during today's 5.10.266-rc1 testing... Honestly, I wouldn't have considered backporting either as b460b15b3cc2 ("i2c: imx: separate atomic, dma and non-dma use case") looks too big to backport to me, so I definitely wouldn't have done it before, but that ship has sailed (it's in the 5.10 -rc right now, but it's been merged a couple of weeks ago in higher versions stables), so at this point I don't think it's worth reverting either and we might as well keep falling forward... tl;dr: If maintainers agree, I can send these two for a future 6.6/6.12: 5f5c2d4579ca ("i2c: imx: prevent rescheduling in non dma mode") 07fd9385f0d8 ("i2c: imx: fix locked bus on SMBus block-read of 0 (IRQ)") Thanks, -- Dominique Martinet | Asmadeus