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 9EF43C4452B for ; Tue, 21 Jul 2026 20:31:39 +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-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=f/6dlNNzxrep/I+kUXeBP0Zntpy18OdT5rMs8LfTOhI=; b=DQ9sHePrazClDGpb9aCbP6ZA8j apX8/UBLPgVaot1QrM5z0R+7a8wdEbth4PyKonnDyAZJdcXsspRh08I7javkukiVtPAozOUb/O0m+ 1609y56sh1hlwzDguyeLbd7YbvCpfhOsfJwAJQxpV1pzNy8Zy4W3pzRHF6d4KNVQFmxNFexI9WyHr e2jPTvzQuTto9eyW27RWYWOR4PypNSqYVR7ugFqzERlkFU0/4hFBGIim0QRrnRb+Ht8XsDUrFy849 q+uAmxU1idDkb87PsThq3Spz9kvNRAxiZe+CWRv0Q4gi5SpSG95qX44P03Xn/KofH0qfa58q+/0x/ XRK8bfsA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wmH7l-0000000ANyN-1Blr; Tue, 21 Jul 2026 20:31:33 +0000 Received: from mgamail.intel.com ([198.175.65.20]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wmH7i-0000000ANxt-485y for linux-arm-kernel@lists.infradead.org; Tue, 21 Jul 2026 20:31:32 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1784665891; x=1816201891; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=mELpT8EvpAt86dh+Sl+XOiKX3cuLi6TaXGjWeybKb3c=; b=iP4XN+Igw1puPa+uAtQgahHWgeJPBRGQPWOVSS2PPn1dSLvTZC6fZfoL +VY0PY6Ihacw+Llux7Kd8Lf7vG9M8kCm1ZJL3FflZHzyJo3A746TjC7g/ VIOpWjyv2ANzhqHWTA36h/2evu0J30PjPJDGYeDpyat2kOUk+6Gw/pnjZ SMrbkNmpBOMWRD1AI0dli7BCWk5HgkRxIxpc/R81tmXVKKruBug10WezN j0fqcrGg3FWEdHO9gKxQlv13P61Z/hJizMUy9cclJUFbzlOv2nlPkkXJO 5pyJVSiLE7cQJ1mI5lPMXQ7i2a7/bGN5jNrzz+vV4nZHXzVGfrEaQj1gf w==; X-CSE-ConnectionGUID: DOSBuig1RdCskQi+d2DcYw== X-CSE-MsgGUID: Qfw9B4eMQ1ikZIhKZEKGZQ== X-IronPort-AV: E=McAfee;i="6800,10657,11853"; a="85046555" X-IronPort-AV: E=Sophos;i="6.25,177,1779174000"; d="scan'208";a="85046555" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by orvoesa112.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jul 2026 13:31:30 -0700 X-CSE-ConnectionGUID: iT9pIwoOSTusznNhX95K7g== X-CSE-MsgGUID: 1l8sK7okT1O+xBqBdpftvA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,177,1779174000"; d="scan'208";a="257940865" Received: from ncintean-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.245.67]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jul 2026 13:31:27 -0700 Date: Tue, 21 Jul 2026 23:31:25 +0300 From: Andy Shevchenko To: "Shih-Yuan Lee (FourDollars)" Cc: Mark Brown , Mika Westerberg , Lukas Wunner , Daniel Mack , Haojian Zhuang , Robert Jarzmik , linux-arm-kernel@lists.infradead.org, linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v16 5/7] spi: pxa2xx: disable DMA for Apple MacBook8,1 Message-ID: References: <20260720162117.32304-1-fourdollars@debian.org> <20260720162117.32304-6-fourdollars@debian.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260721_133131_058177_3D67C64D X-CRM114-Status: GOOD ( 19.19 ) 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 On Tue, Jul 21, 2026 at 10:49:17PM +0800, Shih-Yuan Lee (FourDollars) wrote: > On Tue, Jul 21, 2026 at 3:27 AM Andy Shevchenko > wrote: > > On Tue, Jul 21, 2026 at 12:21:14AM +0800, Shih-Yuan Lee wrote: ... > Thank you for the review and feedback. > > Regarding your question about why DMA fails on this hardware, I have > just sent a detailed reply to Lukas in this thread outlining our > physical verification findings. In short, I confirmed that the > DMA controller's physical interrupt line is not functioning on this > motherboard, It might be wrongly described in ACPI tables, but in HW it works. > and macOS and Windows 10 also completely bypass the DMA > controller. Please refer to that email for the DMAR/IOMMU and > cross-OS analysis details. > > Regarding your other comments: > 2. The force_pio Module Parameter: > The original spi-pxa2xx driver is designed to hardcode DMA usage if > DMA channels are available. I introduced the force_pio module > parameter for two reasons: > • It serves as a diagnostic tool for users on similar hardware to > easily test and verify if their issues are related to DMA. > • It allows developers to easily test and debug the PIO code path on > DMA-capable LPSS hardware to prevent regressions. > > That being said, if module parameters of this type are strictly not > preferred, I am completely fine with removing force_pio and keeping > only the DMI-based quirk for the MacBook8,1. Please let me know your > preference. Neither is preferred until we will fully understand what's going on there. Yes, DMI quirk is a last resort, but to come to that we need to try better options. See my other reply about the DMA case. -- With Best Regards, Andy Shevchenko