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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4AA1C64EB4 for ; Fri, 30 Nov 2018 13:16:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 95D4620867 for ; Fri, 30 Nov 2018 13:16:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 95D4620867 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726808AbeLAA0J (ORCPT ); Fri, 30 Nov 2018 19:26:09 -0500 Received: from mail.bootlin.com ([62.4.15.54]:52527 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726070AbeLAA0J (ORCPT ); Fri, 30 Nov 2018 19:26:09 -0500 Received: by mail.bootlin.com (Postfix, from userid 110) id B27A6207B0; Fri, 30 Nov 2018 14:16:50 +0100 (CET) Received: from aptenodytes (aaubervilliers-681-1-63-158.w90-88.abo.wanadoo.fr [90.88.18.158]) by mail.bootlin.com (Postfix) with ESMTPSA id 6324B2037D; Fri, 30 Nov 2018 14:16:50 +0100 (CET) Message-ID: <2a52719446c1050990494e44a991acb932da8273.camel@bootlin.com> Subject: Re: [linux-sunxi] [PATCH 14/15] arm64: dts: allwinner: h5: Add Video Engine and reserved memory node From: Paul Kocialkowski To: Chen-Yu Tsai Cc: Linux Media Mailing List , devicetree , linux-kernel , linux-arm-kernel , devel@driverdev.osuosl.org, Mauro Carvalho Chehab , Rob Herring , Mark Rutland , Maxime Ripard , Greg Kroah-Hartman , linux-sunxi@googlegroups.com, Hans Verkuil , Sakari Ailus , Thomas Petazzoni Date: Fri, 30 Nov 2018 14:16:50 +0100 In-Reply-To: References: <20181115145013.3378-1-paul.kocialkowski@bootlin.com> <20181115145013.3378-15-paul.kocialkowski@bootlin.com> Organization: Bootlin Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-453EcI7CdM8GuIru8Jyr" User-Agent: Evolution 3.30.2 Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-453EcI7CdM8GuIru8Jyr Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi, On Thu, 2018-11-15 at 23:35 +0800, Chen-Yu Tsai wrote: > On Thu, Nov 15, 2018 at 10:51 PM Paul Kocialkowski > wrote: > > This adds nodes for the Video Engine and the associated reserved memory > > for the H5. Up to 96 MiB of memory are dedicated to the CMA pool. > >=20 > > The pool is located at the end of the first 256 MiB of RAM so that the > > VPU can access it. It is unclear whether this is still a hard > > requirement for this platform, but it seems safer that way. >=20 > I think we can actually test this. You could move the reserved memory > pool beyond 256 MiB, and have cedrus decode stuff, and try to display > the results. If it's gibberish, or the system crashes, it's likely the > memory access wrapped around at 256 MiB. >=20 > What do you think? I did the test on various platforms and found that starting with the A33, the VPU can map any address in RAM! SO we shouldn't need reserved memory nodes for these devices after all. Cheers, Paul --=20 Paul Kocialkowski, Bootlin (formerly Free Electrons) Embedded Linux and kernel engineering https://bootlin.com --=-453EcI7CdM8GuIru8Jyr Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEJZpWjZeIetVBefti3cLmz3+fv9EFAlwBOEIACgkQ3cLmz3+f v9FV/Af+JpWv2W/HOaxK1G4Ane+uWUNIMUUgOaXhtOWvSfOu9arSCtcVqerpnZHu TegKhEKLo5GMEcEBOFbnqiFEno9JkrY+fN7ukdUp0QGqX8uSry5ehpm/yznNDTnZ IvzNrsRO1CrcC0/YKn3+6hxbcD81wf86ALVtQwpUvVv3FNGsvEaKyi7YKKDNOyQs Yevz1VInlDEXFJ5SXmR99LMbAyjNBt7UtHVM5jKODv3lkdXyAta5MGCaRlv8oqxk hZnEe5M4mPns7vmNTa/wM0+zHkAORNs9IoOTepMep2f9pmMNq9qw03PT6hV0bxcU 2ZgSh2jiSJBB8jJk+VhAAUmB+iS8qg== =wjcm -----END PGP SIGNATURE----- --=-453EcI7CdM8GuIru8Jyr--