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 D2358C433EF for ; Wed, 1 Dec 2021 17:58:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To: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=G8ndOK5t1AVWvsYvwMDzDtZr45UAmqPcTIZCbKMIPCw=; b=4HSe3GkXIqIdNg 4dgVv11UNvHHvrmSXDEf3IU7MkgRJAElfKsbKU57JfuMD6k0QRy9ck1VG3FAwe9pw7PTsSxR2q4dZ fdW4404wJy2K5B0qAcVN00ifumISciaxFCrQklwbseuZgPknCxb3DiwQU/8U5AYD+3QJiX1X2pvMT HeVZ9q2llIWrpBewiJ2VjF87b4z3Z6zUBfyFv0lB2ZpT+VbiTU2eq6KTjRc/C08Sb9cF3l17W+M7Z RbbI8la9DQJQbYDEatWZgj5K7YKMncI66XNJW2v0l9Q3LIjJaBNkQ2LqfQ9s3WCm15BICtauM46GA SVIr8kKHCu+7weOe34iQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1msTqT-009dFp-Pd; Wed, 01 Dec 2021 17:56:41 +0000 Received: from rosenzweig.io ([138.197.143.207]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1msTqP-009dDs-U9 for linux-arm-kernel@lists.infradead.org; Wed, 01 Dec 2021 17:56:39 +0000 Date: Wed, 1 Dec 2021 12:56:26 -0500 From: Alyssa Rosenzweig To: Mark Rutland Cc: Marc Zyngier , linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Will Deacon , Hector Martin , Sven Peter , Rob Herring , Thomas Gleixner , Dougall , kernel-team@android.com Subject: Re: [PATCH v2 8/8] drivers/perf: Add Apple icestorm/firestorm CPU PMU driver Message-ID: References: <20211201134909.390490-1-maz@kernel.org> <20211201134909.390490-9-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211201_095638_055522_DD8C0DC1 X-CRM114-Status: GOOD ( 12.57 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org > > Add a new, weird and wonderful driver for the equally weird Apple > > PMU HW. Although the PMU itself is functional, we don't know much > > about the events yet, so this can be considered as yet another > > random number generator... > > It's really frustrating that Apple built this rather than the architected PMU, > because we've generally pushed back on IMPLEMENTATION DEFINED junk in this > area, and supporting this makes it harder to push back on other vendors going > the same route, which I'm not keen on. That, and the usual state of IMP-DEF > stuff making this stupidly painful to reason about. Rules can be a bit stricter for vendors than for ragtag reverse-engineers. The kernel community can push back on vendor's choices because vendors have the power to choose otherwise. But reverse engineers' hands are sometimes forced by bad vendor decisions; rejecting the driver means mainline can never support the hardware. I believe there's precedent for distinguishing these cases, at least in the graphics subsystem. I don't know if this applies to this driver. I only wish to offer a rebuttal to a future vendor trying to mainline something questionable with the defence "Asahi Linux / Nouveau / ... did it, so we can too". (This will be relevant to the Apple M1 display controller driver, which would be a hard NAK if submitted by Apple...) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel