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 88275F3094F for ; Thu, 5 Mar 2026 11:53:45 +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:From:References:Cc:To: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=fkqhgxO0bF57Oug/fKMF2QoeVBKqW5CR9ti4ufycx2g=; b=mJKV9a/rRvbktG /GsjhIZ5b/rMEebWj3R1dbNH1OLvMR1lobIjHu5SJqRykoh/PIsPVEr0JulAxixCYYcdRGMtZX83C LHy4DNx36GKz54LJEziLF2W8XhWN4+dwN6z6IdE/NdHV3ONDRZ22kDir1V4ihOA/fsYKCktPw5TjJ rx8KmRTTinBcRvl9tKru6Fd3HEHTs0T/Vj4j2JYUf0m3aAAV/YpsSRPWgx4t0uIA5OVwSnVW97QIV w9oSpGnqPG2j3xU5XGn/9h2q3CkB9L0oBJCu99nRdZbZhUuYKy07VBUnWLDSLrxL+x3it4U27wkuy EggmunDibT6dyJrnrulQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vy7Gs-00000001i9k-49wf; Thu, 05 Mar 2026 11:53:39 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vy7Gr-00000001i9I-0pmv; Thu, 05 Mar 2026 11:53:38 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 44F7744484; Thu, 5 Mar 2026 11:53:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C262AC116C6; Thu, 5 Mar 2026 11:53:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772711616; bh=Vokr7pE3jEjoiqQGZNJz/o38aeGgsCzeWhivmvmLiz0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=lc1ZWWwh1K+uDC5GITnGWwSlMopayI5NZ65uBO+3ORUFnrdUKiJiEjwIR+Ijv5UMB 1Plrs8An5KzFFWD1x5fiBrENeqRigsixsL+2KkeQ7WpUfiRHI0/F6WXxB2RF1EL5kl WAyzIV3UFQeBUDzTlXHzGu+jyQa66XfHqxZJGfBSyEliiTLZMZw2R9ft9pwOs4Bqre NImYGz5NVJgHQYFuL7O48DJDox9lPSalz55jrUUFnZwbcJg6PphNgz8xEzS87VES3h eGjFf0e3OyZzfKqOrMa9NnmWNhlVnH0R70ARq0c2tUWA+8A9iiuaFKZ8T2PcDer0t0 +y54AZX01CRzw== Message-ID: Date: Thu, 5 Mar 2026 12:53:30 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v4 1/4] media: dt-bindings: Add Amlogic V4L2 video decoder To: Neil Armstrong , Zhentao Guo , Mauro Carvalho Chehab , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Kevin Hilman , Jerome Brunet , Martin Blumenstingl Cc: linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-amlogic@lists.infradead.org References: <20260213-b4-s4-vdec-upstream-v4-0-c7112d00d662@amlogic.com> <20260213-b4-s4-vdec-upstream-v4-1-c7112d00d662@amlogic.com> <75e55ceb-e6dd-47b5-a829-66f6fbb3e13e@amlogic.com> <2f68ee18-e9d9-4da6-900c-93a7663b3c9d@kernel.org> <598c161c-d157-40e5-992c-912540589d7e@amlogic.com> <58d57a6c-7c69-4f5b-a4c2-f34ef0238511@kernel.org> <26d0f52e-3681-46ce-b0dc-0cb020e8d9a1@amlogic.com> <69900d76-3820-467a-9fbc-13f79189df2f@kernel.org> <278f5018-9183-4eeb-bde1-7c19adecab06@linaro.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-amlogic" Errors-To: linux-amlogic-bounces+linux-amlogic=archiver.kernel.org@lists.infradead.org On 05/03/2026 12:35, Neil Armstrong wrote: > On 3/5/26 12:08, Krzysztof Kozlowski wrote: >> On 05/03/2026 12:01, Zhentao Guo wrote: >>> >>> 2. Why canvas is needed? >>> >>> 1. Since the ARM IOMMU HW is not integrated into the Amlogic SOCs,we >>> need canvas to prevent the DDR memory used by the decoder from being >>> rewrote by other hardware. Canvas provides the decoder with a >>> configurable DDR memory range, as well as hardware-based detection >>> and blocking for out-of-bounds access. >>> 2. From the diagram above, we can see a lite CPU called AMRISC. AMRISC >>> is the controller of the decoder HW and the decoder driver needs to >>> access the decoder hardware through AMRISC. However, AMRISC is a >>> 16-bit CPU and cannot directly handle 32-bit or 64-bit physical >>> addresses. Therefore, canvas is required to convert the addresses >>> into index to facilitate processing by the AMRISC core. >> >> This suggests "Canvas" is IOMMU, thus use proper IOMMU abstractions and >> you cannot have own phandle for it. > > > No it is not, canvas was used for a long time for the display and video processing side. > > It's absolutely not like an IOMMU, the diagram is quite clear. The diagram and all descriptions points to memory mapping... "Canvas index is basically a reference to a memory region and its configurations." "Memory access through canvas has HW out-of-boundary check. " "Canvas provides the decoder with a configurable DDR memory range" "canvas is required to convert the addresses into index to..." so it is not a random phandle either. Best regards, Krzysztof _______________________________________________ linux-amlogic mailing list linux-amlogic@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-amlogic