From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.14]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 613CB190059 for ; Tue, 18 Mar 2025 03:08:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.14 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742267309; cv=none; b=rTh6uDNnAACjhPa2jWz7cUHs+/gFV7NYfxc35LcIkkm4Bi3g0zEYKyJQr4J5c3dh9gIN+MenTYrqxxi1rCTLMNtbbCrNSUXZFUsoMeH9QKhuA7VF/R3FxMXmUMTddFUTJsCtwiNVQCaM/0WPzRbG47ij9JiM/oVVSnlL2aZfVRU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742267309; c=relaxed/simple; bh=Dw6S7S52G3ZDoXdOVfRFcW+kfnjTlmEREWykvWpZwHQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=IY9/f1BCcIupjSSZSKFVT84TZvhIre2ItMRGC7sItpD3dQEIHdsK5G1sE3YKVaAp/Xr8n/cet4BDz3y0Fmc7NKfS0eCFZ1NHtuKZ/QaPTmlWJZXpOIrNtAYrQMdlGjx3wPl6Ad1wjNzmw49mZHVATO2TyWhaCtpQ1MWxpTapiFg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=U650Wet6; arc=none smtp.client-ip=192.198.163.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="U650Wet6" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1742267307; x=1773803307; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=Dw6S7S52G3ZDoXdOVfRFcW+kfnjTlmEREWykvWpZwHQ=; b=U650Wet65jMxoetQLTVhi50XAPfOwJxGUsRp5r3N1lF4HPOaQFD4s+3j JSn0zoV1TChOgKMhR34IuGMmnkWofuzIljAz2YSKVM4cG3LxXN9vGQbnu g6FQqv2evXXv+Xk64QHMef4RancbsiHUbvPlVgmEwODsm4JUvIExiOaX3 12XK+2C1avlgi4DYNPa8QYCrUCCeDqrAA15NZZsf0ETs2AK6e7kqtpNr5 VDZEDqpXsYT0g7xCshFTdkQhU0QdRD0QhdUCC9MazGrmmzcVbENzgoPBb DefS5ULgKRBkgiAad4Qd9Z0YoYh+ot/YaKMUPIEbf6xBF9QbJzgPG0H2x w==; X-CSE-ConnectionGUID: KL2r/ALFSmKgbT6F+ojgBQ== X-CSE-MsgGUID: rpVG5yIDT7iEBvCpnY1mOQ== X-IronPort-AV: E=McAfee;i="6700,10204,11376"; a="43578878" X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="43578878" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by fmvoesa108.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 20:08:26 -0700 X-CSE-ConnectionGUID: mufbdTy5TN28CvlW/HBJ6w== X-CSE-MsgGUID: QJK/d4+TSceQ7fs/ToYYvg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,255,1736841600"; d="scan'208";a="126779324" Received: from aschofie-mobl2.amr.corp.intel.com (HELO aschofie-mobl2.lan) ([10.125.109.156]) by fmviesa005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2025 20:08:26 -0700 Date: Mon, 17 Mar 2025 20:08:24 -0700 From: Alison Schofield To: Jonathan Cameron Cc: Davidlohr Bueso , Dave Jiang , Vishal Verma , Ira Weiny , Dan Williams , linux-cxl@vger.kernel.org Subject: Re: [PATCH v2] cxl/region: Allow 6 & 12 way regions on 3-way HB interleaves Message-ID: References: <20250306232239.2609017-1-alison.schofield@intel.com> <20250314120036.000034a9@huawei.com> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250314120036.000034a9@huawei.com> On Fri, Mar 14, 2025 at 12:00:36PM +0000, Jonathan Cameron wrote: > On Thu, 6 Mar 2025 15:22:37 -0800 > alison.schofield@intel.com wrote: > > > From: Alison Schofield > > > > The CXL driver requires the granularity of a region and its root > > decoder to be the same. This is particularly restrictive for 3-way > > host bridge interleaves where the only spec defined interleave > > configurations for creating 6-way and 12-way regions on a 3-way HB > > interleave require mixed granularities. > > > > CXL 3.2 Specification 9.13.1.1: > > Legal Interleaving Configurations: 12-way, 6-way, and 3-way > > Ah this is finally a valid reason to do coarser interleave first > (going away from host). That was subject of long discussions way back > when original interleaving code was discussed (mostly because > my mental model did it that way around and I couldn't follow what > the kernel code was doing). > > We 'could' revisit allowing this more generally - at least for > already configured set ups. Only real reason for that is > either that someone ships a config that does it for a different > case, or that we want to avoid special casing 3*x cases. Hi Jonathan, I'll bring these configs up as an OPEN at the upcoming community collab, and hope you can elaborate more there. --Alison > > Jonathan