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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 25460C53200 for ; Wed, 29 Jul 2026 15:34:33 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id DE1DA10ECAC; Wed, 29 Jul 2026 15:34:32 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="J+KAafDN"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.14]) by gabe.freedesktop.org (Postfix) with ESMTPS id C48C710ECAC for ; Wed, 29 Jul 2026 15:34:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1785339272; x=1816875272; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=DcXiM0YjfvTd8FCo+yjKRVGvxoViQMnPMrkLHYDFAQg=; b=J+KAafDNqNbp9QIS/KtVonzYPdkPh1qozUEfCYKwTVSsEVotz3cCszQT dzDNVaO6b7znr3JPNNRsxkNfNppcmYGd/k5oGz369BpARE6CPjFOX418h r9Xeft1tUdM/e8XKDtXP2nbrX81DDFlUkrmm7zO8fDez53tesfe+Hp5Qq Vs3n9Sdk77VkzAX4tHjEKo5kbIQFoHaGrCHk517yp/8fV6L1purtMOUVa YPcNBODOTXmqBSOETXPwai2IND9/SumWqjrJ9VM3FSd/QuLFyC4zodeZt xRPDbKQnwjJ9W83ruSMfD9Z4LYXX4cy0NT+9NUNFLm0pAD0rpYEVHCkub Q==; X-CSE-ConnectionGUID: nxPfIukLR2q1OGUtFEVorg== X-CSE-MsgGUID: aQcExwj2QBOswuRDVkNfWQ== X-IronPort-AV: E=McAfee;i="6800,10657,11859"; a="85985050" X-IronPort-AV: E=Sophos;i="6.25,192,1779174000"; d="scan'208";a="85985050" Received: from orviesa004.jf.intel.com ([10.64.159.144]) by fmvoesa108.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2026 08:34:31 -0700 X-CSE-ConnectionGUID: MfVhvtpfR+6oenkZMr0WSA== X-CSE-MsgGUID: F3eBR584QHSAkKEn1S9pPw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,192,1779174000"; d="scan'208";a="263851686" Received: from black.igk.intel.com ([10.91.253.5]) by orviesa004.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2026 08:34:29 -0700 Date: Wed, 29 Jul 2026 17:34:26 +0200 From: Raag Jadav To: Heikki Krogerus Cc: Matthew Brost , Thomas =?iso-8859-1?Q?Hellstr=F6m?= , Rodrigo Vivi , Mika Westerberg , Andy Shevchenko , Andi Shyti , Ramesh Babu B , "Michael J. Ruhl" , linux-kernel@vger.kernel.org, intel-xe@lists.freedesktop.org, stable@vger.kernel.org Subject: Re: [PATCH v6 3/3] drm/xe/i2c: Keep the i2c controller always enabled Message-ID: References: <20260722133554.2079612-1-heikki.krogerus@linux.intel.com> <20260722133554.2079612-4-heikki.krogerus@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260722133554.2079612-4-heikki.krogerus@linux.intel.com> X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Wed, Jul 22, 2026 at 03:35:54PM +0200, Heikki Krogerus wrote: > Some platforms make an assumption that the i2c controller's > enabled state indicates also the power state of the > controller. This can create a problem when the controller is > in disabled state, because the hardware may assume > incorrectly that it is then also in low-power state. > > To fix this, the controller is kept enabled by taking over > the IC_ENABLE register. The controller has to be disabled > when the configuration is updated and when the target > address or the slave address are assigned, so disabling it > when IC_CON, IC_TAR or IC_SAR registers are programmed, and > then re-enabling it again. > > Fixes: f0e53aadd702 ("drm/xe: Support for I2C attached MCUs") > Cc: stable@vger.kernel.org > Signed-off-by: Heikki Krogerus I'll rely on Andy and Mika's disposition on this one. Raag