From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr2-f35.google.com (mail-wr2-f35.google.com [74.125.225.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 31E5F4334AD for ; Fri, 2 Oct 2026 07:53:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.225.99 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790927593; cv=none; b=POcn7BbEkSQoD3afYkZdz77+2noaAsDA1UrZFHKZ2YH+KuULhn6d8Xu/5Qk89Hbv+bJvwVmpL9H+L6VIaDmcBCneuLcqwagBBr/8MuF3gyaaxVL8ovAqSpnm7XWY5LvBoZAnLxRG1Zy0EoZzt/e87Kl0ZmfF4EfA7f6UcmLLPLk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790927593; c=relaxed/simple; bh=ag+sZnjQWuyPSA4K+zz6QgF7pFR9QYHKz6IJ/tFAQLQ=; h=Message-ID:Date:MIME-Version:From:Subject:To:Cc:References: In-Reply-To:Content-Type; b=O86vhInXQRS9Y46cZWb7/pMJEsUn1YaTfUIDf1eHQaea8BxIB9ZOmf9y3/N2TeSk6E3uyk1r4aouIiToB1WKZezjyvklXi/mNEyAHbvtOFfnfxBXsgkFm8c3Abj5AriIxnnfKFYlSyaF5GvJZ0mrTak1tfyPi+FjO763DcXCC6o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org; spf=pass smtp.mailfrom=linaro.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b=LW3pd3dG; arc=none smtp.client-ip=74.125.225.99 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linaro.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="LW3pd3dG" Received: by mail-wr2-f35.google.com with SMTP id ffacd0b85a97d-48882c1f2baso2621300f8f.1 for ; Fri, 02 Oct 2026 00:53:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1790927590; x=1791532390; darn=lists.linux.dev; h=content-transfer-encoding:content-type:in-reply-to:organization :autocrypt:content-language:references:cc:to:subject:reply-to:from :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to:content-type; bh=URK5hJaiby1L1KtEXv2HgCyxpcy+Et12hnj8ni1/g3I=; b=LW3pd3dGTIdu6otet1KJDXTSFS/laJ2ljOr8yKjSJt0MJnvOiXYCTCyFZs4Qr0trvG k6241PwHr2EEg81KMzSG/5UZIGNhuU9mNpZcNCIBVMrxVK/JcrXX6GO34UeJXGSdth2I Ob8JpzVXT4pa/AqWUfyk0JxOuDBXcvcn/NkC77Fl/La1Worf2APdfWvhCU0A3mg5HuUo s00Xi1y+3VauFp5iqROpZKe7s1iA4AzFY/5ky5mN370IXaHCOYvwLJ9mHZq/rgkwO4uh UZXO37xXpmRAEteBxGTS5vocLj9EAxbV6ygFtztO4k6Xk8xacTlO9oQJCgHqBt99Lcwd 9Kfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790927590; x=1791532390; h=content-transfer-encoding:content-type:in-reply-to:organization :autocrypt:content-language:references:cc:to:subject:reply-to:from :user-agent:mime-version:date:message-id:x-gm-gg:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to:content-type; bh=URK5hJaiby1L1KtEXv2HgCyxpcy+Et12hnj8ni1/g3I=; b=dq9bnW2wUQl/LNQW19misfY11kRPUitQ0Zj2vTtTQ5rXWD0YNHgJ6lObKpewpx3tj+ Hq8FIMOwHK1itDJM/cqH5w4cwM7lsyBieoiaqOtYYguyQxyeneVHklAGZXsJC/sCTNnq 0Q3JcSK9DdRB7W1VbkcEX1dnTsqTAEBHWPwIkdxBGNNu3h15QYRjwLia3/4LcOi2x+6Q IaaIiIUpHubZFv28FGeQh0l2nbKBexnIeNgGjoc+CmRBcVBGMyFW5LXToGQWFohHBKY0 AE0UGUph1eJS6dAcq2hLzykVlDlWWnYQVXZ6hozxBoLjPU2Z2aRyytUwvpb3hV7DMqgU F/cQ== X-Forwarded-Encrypted: i=1; AKwUvBxS/rBZwlJ8HOs0f1jFFmbRHAgdII6JbencV1VR1mFB4QZXdJ/m5GdIYg/R+UOImlJ8zXi6@lists.linux.dev X-Gm-Message-State: AFq9FYIR5QvpjtnpBkU2Mt5WoEMt9w3zcIoySoBSRiBvthXUnnOzfdze Vb0I0f/oPVxVwSt3Iunaq4j/jkq34Gt6v+1XacUr5yxtMc0o0gYSmJBHIjCyHKXtmX4= X-Gm-Gg: AYBFou3jT92/XPT5mL1R+Z5ZlNidd5Iz6/I8Z/Ah6OsA8glful86U4iRUUg64N4es3f htxM8PDcn/wweHPHzfWcs+eFHDAxQDqNdvnpD5uDDlVs+8sNUShZIcrK8ZBI8ELHme7bq1gPbc0 oTn5d46NuWpIGNga/aH5N/KYRT5ZIXuQYPAug558SsrJq6eg5IuDf+GCeSpBPt6Nm1t3TpgCYDE SkQ2SWPEhUUCeUDrEy/fv8rPoAfj2fgD/3avmatkj+qF6tZ/FHF/TFTQ0R/W/k1uU/u5OGvp2oN h1OIJ2NGxLjbJEAdEGFjnvrVVIWNIzDJJ6WbtS7DoA+FbjjzNQH89955dG4Xg7VfplM2FCVI+r6 qVUnazODpDR29E+9Fuw18ZijELiAwyZndF0/+sb/HYOcSufGGud8beeXOzvU0qu6MowRFP/gI36 xfKecLc4t7sGyqkNs0jo21h7ipDVt8IMbahwdOLsksDZuXZQZjedRTxRsXaq0HMV3Lk7cDzzpbL FPZ87j7DLqYRsibi0d6kfHmxp2sew33seSauxt/9zNes4sPbE8O X-Received: by 2002:a05:6000:46da:b0:48b:68:592e with SMTP id ffacd0b85a97d-48b126c2526mr2669376f8f.4.1790927590269; Fri, 02 Oct 2026 00:53:10 -0700 (PDT) Received: from ?IPV6:2a01:e0a:106d:1080:2f62:6d3:721b:8c9e? ([2a01:e0a:106d:1080:2f62:6d3:721b:8c9e]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48b380f0ab7sm3840821f8f.7.2026.10.02.00.53.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 02 Oct 2026 00:53:09 -0700 (PDT) Message-ID: Date: Fri, 2 Oct 2026 09:53:07 +0200 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Neil Armstrong Reply-To: Neil Armstrong Subject: Re: [PATCH 0/6] drm/bridge: Add a BPF-based MIPI-DSI panel driver To: Javier Martinez Canillas , Maxime Ripard Cc: Benjamin Tissoires , Jessica Zhang , David Airlie , Simona Vetter , Maarten Lankhorst , Thomas Zimmermann , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Florian Fainelli , Broadcom internal kernel review list , Andrzej Hajda , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Luca Ceresoli , Albert Esteve , Dave Stevenson , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, llvm@lists.linux.dev, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org References: <20260928-drm-mipi-dsi-panel-ebpf-v1-0-5244926aace4@kernel.org> <6b80cb97-6706-412a-b013-9423f6f75153@linaro.org> <0259fe4b-3118-4ab0-9b62-55101bfd7f33@linaro.org> <674314b4-6b80-4b3a-ac15-eefd31cea607@linaro.org> <828c9108-2db1-45a6-9301-19159a094301@linaro.org> <2bd17843-4a65-49b0-9e10-7b73afb206b6@linaro.org> Content-Language: en-US, fr Autocrypt: addr=neil.armstrong@linaro.org; keydata= xsBNBE1ZBs8BCAD78xVLsXPwV/2qQx2FaO/7mhWL0Qodw8UcQJnkrWmgTFRobtTWxuRx8WWP GTjuhvbleoQ5Cxjr+v+1ARGCH46MxFP5DwauzPekwJUD5QKZlaw/bURTLmS2id5wWi3lqVH4 BVF2WzvGyyeV1o4RTCYDnZ9VLLylJ9bneEaIs/7cjCEbipGGFlfIML3sfqnIvMAxIMZrvcl9 qPV2k+KQ7q+aXavU5W+yLNn7QtXUB530Zlk/d2ETgzQ5FLYYnUDAaRl+8JUTjc0CNOTpCeik 80TZcE6f8M76Xa6yU8VcNko94Ck7iB4vj70q76P/J7kt98hklrr85/3NU3oti3nrIHmHABEB AAHNKk5laWwgQXJtc3Ryb25nIDxuZWlsLmFybXN0cm9uZ0BsaW5hcm8ub3JnPsLAkQQTAQoA OwIbIwULCQgHAwUVCgkICwUWAgMBAAIeAQIXgBYhBInsPQWERiF0UPIoSBaat7Gkz/iuBQJk Q5wSAhkBAAoJEBaat7Gkz/iuyhMIANiD94qDtUTJRfEW6GwXmtKWwl/mvqQtaTtZID2dos04 YqBbshiJbejgVJjy+HODcNUIKBB3PSLaln4ltdsV73SBcwUNdzebfKspAQunCM22Mn6FBIxQ GizsMLcP/0FX4en9NaKGfK6ZdKK6kN1GR9YffMJd2P08EO8mHowmSRe/ExAODhAs9W7XXExw UNCY4pVJyRPpEhv373vvff60bHxc1k/FF9WaPscMt7hlkbFLUs85kHtQAmr8pV5Hy9ezsSRa GzJmiVclkPc2BY592IGBXRDQ38urXeM4nfhhvqA50b/nAEXc6FzqgXqDkEIwR66/Gbp0t3+r yQzpKRyQif3OwE0ETVkGzwEIALyKDN/OGURaHBVzwjgYq+ZtifvekdrSNl8TIDH8g1xicBYp QTbPn6bbSZbdvfeQPNCcD4/EhXZuhQXMcoJsQQQnO4vwVULmPGgtGf8PVc7dxKOeta+qUh6+ SRh3vIcAUFHDT3f/Zdspz+e2E0hPV2hiSvICLk11qO6cyJE13zeNFoeY3ggrKY+IzbFomIZY 4yG6xI99NIPEVE9lNBXBKIlewIyVlkOaYvJWSV+p5gdJXOvScNN1epm5YHmf9aE2ZjnqZGoM Mtsyw18YoX9BqMFInxqYQQ3j/HpVgTSvmo5ea5qQDDUaCsaTf8UeDcwYOtgI8iL4oHcsGtUX oUk33HEAEQEAAcLAXwQYAQIACQUCTVkGzwIbDAAKCRAWmrexpM/4rrXiB/sGbkQ6itMrAIfn M7IbRuiSZS1unlySUVYu3SD6YBYnNi3G5EpbwfBNuT3H8//rVvtOFK4OD8cRYkxXRQmTvqa3 3eDIHu/zr1HMKErm+2SD6PO9umRef8V82o2oaCLvf4WeIssFjwB0b6a12opuRP7yo3E3gTCS KmbUuLv1CtxKQF+fUV1cVaTPMyT25Od+RC1K+iOR0F54oUJvJeq7fUzbn/KdlhA8XPGzwGRy 4zcsPWvwnXgfe5tk680fEKZVwOZKIEuJC3v+/yZpQzDvGYJvbyix0lHnrCzq43WefRHI5XTT QbM0WUIBIcGmq38+OgUsMYu4NzLu7uZFAcmp6h8g Organization: Linaro In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/2/26 09:37, Javier Martinez Canillas wrote: > Neil Armstrong writes: > > Hello Neil, > >> On 10/1/26 08:50, Maxime Ripard wrote: > > [...] > >>>> >>>> I don't want to add a supplementary maintenance burden for the sake of using a cool >>>> technology which has serious drawbacks and dependencies on user-space even if looks >>>> really cool. >>> >>> Spoiler alert: v2 won't. I've got the in-kernel loader to work and thus >>> you can have a built-in panel driver that works without user-space >>> intervention. So this is not a topic of discussion anymore. >> >> It will still have users-space dependency, meaning the BPF files will need to >> exist in the fs when drivers probes. >> > > It doesn't have to AFAIU. The BPF programs could be built into the kernel > image, just like firmware binaries could be built-in as well. Right so my main question still is: what does it solve exactly ? All the descriptions I saw so far is that it simply moves the panel C code to a BPF code with no other additions. I still don't have a clear view of what is precisely solves. It adds some complexity to load those BPF driver, adds some maintenance complexities since with every API change we will need validate BPF still works in addition to C (and maybe one day Rust). As the maintainer of the panels, merging a bunch of new panels at each releases and helping migrating to newer and modern way to interact with panels, I think I have the right to express my interrogations. I'm clearly not the oldest kernel contributor & maintainer around here, but the main interrogation I have when submitting, reviewing and merging is : does it really solve something efficiently. I don't want people to be frustrated by my review and question, but I feel I'm allowed to say I'm not convinced about this solution. Neil > >> Neil >> >