From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3082D2ED865; Fri, 29 Aug 2025 13:41:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756474866; cv=none; b=U751J6CyqylN+RUszUsJavLttJHziF1SsRgx+E8JBOkjq69csPIn9YbLk+8nRbrZER4DQHFUW2g8v5OCAB3DemU5hV/XFOlTtLO0oIl3tlnnnv9YToeaKsXshnNsMmaYHuVq2A/10/FTiRpSS4fw0DBAJkuXD+GIzO44x5BZWDk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756474866; c=relaxed/simple; bh=PTvgbvYm46h9Row2oa+6kFtRNdfQHYUqbqqiQaJEoD8=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=KzfL9FLtvBHXxhyEKvPRCxV++N85mUHF9yiMGVmISU6Bj9BddjawfjRTq8TqzBiXkzqW94wr+UejzT84C59JLzqYjn3deVp0HYkjo1V1ysmXXKvPbKfvQ81JZ5W2TBDpww5K+an/rNtIhwhU4Cjsp7ukjtcPnyZFQyi/hK5c6/4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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(+) >