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 27DCECA0FF9 for ; Fri, 29 Aug 2025 13:41:06 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8929110EBB5; Fri, 29 Aug 2025 13:41:05 +0000 (UTC) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by gabe.freedesktop.org (Postfix) with ESMTP id BF52210EBB5 for ; Fri, 29 Aug 2025 13:41:04 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 130B415A1; Fri, 29 Aug 2025 06:40:56 -0700 (PDT) Received: from [10.1.29.20] (unknown [10.1.29.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 10A813F738; Fri, 29 Aug 2025 06:41:00 -0700 (PDT) Message-ID: Date: Fri, 29 Aug 2025 14:40:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/2] drm/panthor: add custom ASN hash support To: Chia-I Wu , Boris Brezillon , Liviu Dudau , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Herring , Krzysztof Kozlowski , Conor Dooley , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250828201806.3541261-1-olvaffe@gmail.com> From: Steven Price Content-Language: en-GB In-Reply-To: <20250828201806.3541261-1-olvaffe@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 28/08/2025 21:18, Chia-I Wu wrote: > Some socs such as mt8196 require custom ASN hash. I don't know the full details of this, but I'm puzzled by the "require" here. AIUI the "custom ASN hash support" (or L2C_SLICE_HASH as it was renamed) affects the efficiency of the L2 caches in the GPU. It basically determines how addresses are striped over the individual caches. So (unless there is a specific errata) not setting a custom hash will work just fine, but the performance might be slightly reduced. kbase provides both a DT option and a module parameter which can be used to override the defaults (although the parameter descriptions say "for testing" which I think is somewhat telling). How we should describe this somewhat depends on whether this is a specific workaround for a SoC - in which case Boris's suggestion of using a different compatible string and panthor_soc_data seems like a good choice. Or if this is exposed as a general "tuning" parameter, in which case this might be appropriate. I believe the tuning is related to more than just a SoC (the external memory system has an impact). So I guess a DT level knob makes most sense here. Steve > Chia-I Wu (2): > dt-bindings: gpu: mali-valhall-csf: add asn-hash > drm/panthor: add asn-hash support > > .../bindings/gpu/arm,mali-valhall-csf.yaml | 8 ++++++ > drivers/gpu/drm/panthor/panthor_device.c | 28 +++++++++++++++++++ > drivers/gpu/drm/panthor/panthor_device.h | 6 ++++ > drivers/gpu/drm/panthor/panthor_gpu.c | 17 +++++++++++ > drivers/gpu/drm/panthor/panthor_regs.h | 4 +++ > 5 files changed, 63 insertions(+) >