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([2a01:e35:2ec0:82b0:5c5f:613e:f775:b6a2]) by smtp.gmail.com with ESMTPSA id s15sm35271104wrr.45.2020.03.25.03.24.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 25 Mar 2020 03:24:16 -0700 (PDT) Subject: Re: [PATCH v4 7/8] drm/fourcc: amlogic: Add modifier definitions for the Scatter layout To: Simon Ser Cc: "daniel@ffwll.ch" , "dri-devel@lists.freedesktop.org" , "mjourdan@baylibre.com" , Kevin Hilman , "linux-kernel@vger.kernel.org" , "linux-amlogic@lists.infradead.org" , "linux-arm-kernel@lists.infradead.org" References: <20200325085025.30631-1-narmstrong@baylibre.com> <20200325085025.30631-8-narmstrong@baylibre.com> From: Neil Armstrong Autocrypt: addr=narmstrong@baylibre.com; prefer-encrypt=mutual; keydata= xsBNBE1ZBs8BCAD78xVLsXPwV/2qQx2FaO/7mhWL0Qodw8UcQJnkrWmgTFRobtTWxuRx8WWP GTjuhvbleoQ5Cxjr+v+1ARGCH46MxFP5DwauzPekwJUD5QKZlaw/bURTLmS2id5wWi3lqVH4 BVF2WzvGyyeV1o4RTCYDnZ9VLLylJ9bneEaIs/7cjCEbipGGFlfIML3sfqnIvMAxIMZrvcl9 qPV2k+KQ7q+aXavU5W+yLNn7QtXUB530Zlk/d2ETgzQ5FLYYnUDAaRl+8JUTjc0CNOTpCeik 80TZcE6f8M76Xa6yU8VcNko94Ck7iB4vj70q76P/J7kt98hklrr85/3NU3oti3nrIHmHABEB AAHNKE5laWwgQXJtc3Ryb25nIDxuYXJtc3Ryb25nQGJheWxpYnJlLmNvbT7CwHsEEwEKACUC GyMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheABQJXDO2CAhkBAAoJEBaat7Gkz/iubGIH/iyk RqvgB62oKOFlgOTYCMkYpm2aAOZZLf6VKHKc7DoVwuUkjHfIRXdslbrxi4pk5VKU6ZP9AKsN NtMZntB8WrBTtkAZfZbTF7850uwd3eU5cN/7N1Q6g0JQihE7w4GlIkEpQ8vwSg5W7hkx3yQ6 2YzrUZh/b7QThXbNZ7xOeSEms014QXazx8+txR7jrGF3dYxBsCkotO/8DNtZ1R+aUvRfpKg5 ZgABTC0LmAQnuUUf2PHcKFAHZo5KrdO+tyfL+LgTUXIXkK+tenkLsAJ0cagz1EZ5gntuheLD YJuzS4zN+1Asmb9kVKxhjSQOcIh6g2tw7vaYJgL/OzJtZi6JlIXOwU0EVid/pAEQAND7AFhr 5faf/EhDP9FSgYd/zgmb7JOpFPje3uw7jz9wFb28Cf0Y3CcncdElYoBNbRlesKvjQRL8mozV 9RN+IUMHdUx1akR/A4BPXNdL7StfzKWOCxZHVS+rIQ/fE3Qz/jRmT6t2ZkpplLxVBpdu95qJ YwSZjuwFXdC+A7MHtQXYi3UfCgKiflj4+/ITcKC6EF32KrmIRqamQwiRsDcUUKlAUjkCLcHL CQvNsDdm2cxdHxC32AVm3Je8VCsH7/qEPMQ+cEZk47HOR3+Ihfn1LEG5LfwsyWE8/JxsU2a1 q44LQM2lcK/0AKAL20XDd7ERH/FCBKkNVzi+svYJpyvCZCnWT0TRb72mT+XxLWNwfHTeGALE +1As4jIS72IglvbtONxc2OIid3tR5rX3k2V0iud0P7Hnz/JTdfvSpVj55ZurOl2XAXUpGbq5 XRk5CESFuLQV8oqCxgWAEgFyEapI4GwJsvfl/2Er8kLoucYO1Id4mz6N33+omPhaoXfHyLSy dxD+CzNJqN2GdavGtobdvv/2V0wukqj86iKF8toLG2/Fia3DxMaGUxqI7GMOuiGZjXPt/et/ qeOySghdQ7Sdpu6fWc8CJXV2mOV6DrSzc6ZVB4SmvdoruBHWWOR6YnMz01ShFE49pPucyU1h Av4jC62El3pdCrDOnWNFMYbbon3vABEBAAHCwn4EGAECAAkFAlYnf6QCGwICKQkQFpq3saTP +K7BXSAEGQECAAYFAlYnf6QACgkQd9zb2sjISdGToxAAkOjSfGxp0ulgHboUAtmxaU3viucV e2Hl1BVDtKSKmbIVZmEUvx9D06IijFaEzqtKD34LXD6fjl4HIyDZvwfeaZCbJbO10j3k7FJE QrBtpdVqkJxme/nYlGOVzcOiKIepNkwvnHVnuVDVPcXyj2wqtsU7VZDDX41z3X4xTQwY3SO1 9nRO+f+i4RmtJcITgregMa2PcB0LvrjJlWroI+KAKCzoTHzSTpCXMJ1U/dEqyc87bFBdc+DI k8mWkPxsccdbs4t+hH0NoE3Kal9xtAl56RCtO/KgBLAQ5M8oToJVatxAjO1SnRYVN1EaAwrR xkHdd97qw6nbg9BMcAoa2NMc0/9MeiaQfbgW6b0reIz/haHhXZ6oYSCl15Knkr4t1o3I2Bqr Mw623gdiTzotgtId8VfLB2Vsatj35OqIn5lVbi2ua6I0gkI6S7xJhqeyrfhDNgzTHdQVHB9/ 7jnM0ERXNy1Ket6aDWZWCvM59dTyu37g3VvYzGis8XzrX1oLBU/tTXqo1IFqqIAmvh7lI0Se gCrXz7UanxCwUbQBFjzGn6pooEHJYRLuVGLdBuoApl/I4dLqCZij2AGa4CFzrn9W0cwm3HCO lR43gFyz0dSkMwNUd195FrvfAz7Bjmmi19DnORKnQmlvGe/9xEEfr5zjey1N9+mt3//geDP6 clwKBkq0JggA+RTEAELzkgPYKJ3NutoStUAKZGiLOFMpHY6KpItbbHjF2ZKIU1whaRYkHpB2 uLQXOzZ0d7x60PUdhqG3VmFnzXSztA4vsnDKk7x2xw0pMSTKhMafpxaPQJf494/jGnwBHyi3 h3QGG1RjfhQ/OMTX/HKtAUB2ct3Q8/jBfF0hS5GzT6dYtj0Ci7+8LUsB2VoayhNXMnaBfh+Q pAhaFfRZWTjUFIV4MpDdFDame7PB50s73gF/pfQbjw5Wxtes/0FnqydfId95s+eej+17ldGp lMv1ok7K0H/WJSdr7UwDAHEYU++p4RRTJP6DHWXcByVlpNQ4SSAiivmWiwOt490+Ac7ATQRN WQbPAQgAvIoM384ZRFocFXPCOBir5m2J+96R2tI2XxMgMfyDXGJwFilBNs+fpttJlt2995A8 0JwPj8SFdm6FBcxygmxBBCc7i/BVQuY8aC0Z/w9Vzt3Eo561r6pSHr5JGHe8hwBQUcNPd/9l 2ynP57YTSE9XaGJK8gIuTXWo7pzIkTXfN40Wh5jeCCspj4jNsWiYhljjIbrEj300g8RUT2U0 FcEoiV7AjJWWQ5pi8lZJX6nmB0lc69Jw03V6mblgeZ/1oTZmOepkagwy2zLDXxihf0GowUif GphBDeP8elWBNK+ajl5rmpAMNRoKxpN/xR4NzBg62AjyIvigdywa1RehSTfccQARAQABwsBf BBgBAgAJBQJNWQbPAhsMAAoJEBaat7Gkz/iuteIH+wZuRDqK0ysAh+czshtG6JJlLW6eXJJR Vi7dIPpgFic2LcbkSlvB8E25Pcfz/+tW+04Urg4PxxFiTFdFCZO+prfd4Mge7/OvUcwoSub7 ZIPo8726ZF5/xXzajahoIu9/hZ4iywWPAHRvprXaim5E/vKjcTeBMJIqZtS4u/UK3EpAX59R XVxVpM8zJPbk535ELUr6I5HQXnihQm8l6rt9TNuf8p2WEDxc8bPAZHLjNyw9a/CdeB97m2Tr zR8QplXA5kogS4kLe/7/JmlDMO8Zgm9vKLHSUeesLOrjdZ59EcjldNNBszRZQgEhwaarfz46 BSwxi7g3Mu7u5kUByanqHyA= Organization: Baylibre Message-ID: Date: Wed, 25 Mar 2020 11:24:15 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 25/03/2020 10:04, Simon Ser wrote: > On Wednesday, March 25, 2020 9:50 AM, Neil Armstrong wrote: > >> Amlogic uses a proprietary lossless image compression protocol and format >> for their hardware video codec accelerators, either video decoders or >> video input encoders. >> >> This introduces the Scatter Memory layout, means the header contains IOMMU >> references to the compressed frames content to optimize memory access >> and layout. >> >> In this mode, only the header memory address is needed, thus the content >> memory organization is tied to the current producer execution and cannot >> be saved/dumped neither transferrable between Amlogic SoCs supporting this >> modifier. > > I don't think this is suitable for modifiers. User-space relies on > being able to copy a buffer from one machine to another over the > network. It would be pretty annoying for user-space to have a blacklist > of modifiers that don't work this way. > > Example of such user-space: > https://gitlab.freedesktop.org/mstoeckl/waypipe/ > I really understand your point, but this is one of the use-cases we need solve. This is why I split the fourcc patch and added an explicit comment. Please point me a way to display such buffer, the HW exists, works like that and it's a fact and can't change. It will be the same for secure zero-copy buffers we can't map from userspace, but only the HW decoder can read/write and HW display can read. We need a solution for those if we want embedded and secure products to be supported upstream, otherwise they will stay in an obscure off-tree linux tree and for example AOSP support (which will support these secure video buffers) will use these vendor specific hacks. Neil