From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-qt0-f195.google.com ([209.85.216.195]:39883 "EHLO mail-qt0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751530AbeA3J7U (ORCPT ); Tue, 30 Jan 2018 04:59:20 -0500 Date: Tue, 30 Jan 2018 10:59:16 +0100 From: Thierry Reding To: Arnd Bergmann Cc: Maxime Ripard , Linus Walleij , Yong Deng , Mauro Carvalho Chehab , Rob Herring , Mark Rutland , Chen-Yu Tsai , "David S. Miller" , Greg Kroah-Hartman , Hans Verkuil , Randy Dunlap , Stanimir Varbanov , Hugues Fruchet , Yannick Fertre , Philipp Zabel , Benjamin Gaignard , Ramesh Shanmugasundaram , Sakari Ailus , Rick Chang , Linux Media Mailing List , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Linux ARM , "linux-kernel@vger.kernel.org" , linux-sunxi , megous@megous.com, Thomas Petazzoni Subject: Re: [PATCH v6 2/2] media: V3s: Add support for Allwinner CSI. Message-ID: <20180130095916.GA23047@ulmo> References: <1516695531-23349-1-git-send-email-yong.deng@magewell.com> <20180129082533.6edmqgbauo6q5dgz@flea.lan> <20180130075441.rqxzkwero6sdfak6@flea.lan> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="xHFwDpU9dbj6ez1V" Content-Disposition: inline In-Reply-To: Sender: linux-media-owner@vger.kernel.org List-ID: --xHFwDpU9dbj6ez1V Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jan 30, 2018 at 10:24:48AM +0100, Arnd Bergmann wrote: > On Tue, Jan 30, 2018 at 8:54 AM, Maxime Ripard > wrote: > > On Mon, Jan 29, 2018 at 03:34:02PM +0100, Arnd Bergmann wrote: > >> On Mon, Jan 29, 2018 at 10:25 AM, Linus Walleij > >> wrote: > >> > On Mon, Jan 29, 2018 at 9:25 AM, Maxime Ripard > >> > wrote: > >> >> On Sat, Jan 27, 2018 at 05:14:26PM +0100, Linus Walleij wrote: >=20 > >> > >> At one point we had discussed adding a 'dma-masters' property that > >> lists all the buses on which a device can be a dma master, and > >> the respective properties of those masters (iommu, coherency, > >> offset, ...). > >> > >> IIRC at the time we decided that we could live without that complexity, > >> but perhaps we cannot. > > > > Are you talking about this ? > > https://elixir.free-electrons.com/linux/latest/source/Documentation/dev= icetree/bindings/dma/dma.txt#L41 > > > > It doesn't seem to be related to that issue to me. And in our > > particular cases, all the devices are DMA masters, the RAM is just > > mapped to another address. >=20 > No, that's not the one I was thinking of. The idea at the time was much > more generic, and not limited to dma engines. I don't recall the details, > but I think that Thierry was either involved or made the proposal at the > time. Yeah, I vaguely remember discussing something like this before. A quick search through my inbox yielded these two threads, mostly related to IOMMU but I think there were some mentions about dma-ranges and so on as well. I'll have to dig deeper into those threads to refresh my memories, but I won't get around to it until later today. If someone wants to read up on this in the meantime, here are the links: https://lkml.org/lkml/2014/4/27/346 http://lists.infradead.org/pipermail/linux-arm-kernel/2014-May/257200.html =46rom a quick glance the issue of dma-ranges was something that we hand- waved at the time. Thierry --xHFwDpU9dbj6ez1V Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAlpwQfIACgkQ3SOs138+ s6Fh7g/8DFGL0MzPPU8t/wdZQbRgTyDjYLOX2sBH8WYUFlkqDLocFVs58lSMZpiU xD6/muWOblNt9BJX7yd3zcPM4S/sNVTv7VsafkJZ1ssjPRLDwy/WTL2wAwIhOv5t iQUUYFgG8q8YRCaG+xYiDW+1PCA21P8xl57OgfOc7MaqHKwy2Z7Dnq3rE8LUSiBP IZDynIHOMSZRKskwbvdXgCRM56faA81pwYPX+B04kmcVap4ellQ+aYq/t6uDRlpA wmKWxWnCQsrAgpBKBTqARXMFo0XXUo7lzcYsj5AKZFAZZ6uU/DvZm6SryEirr6vh dW7NPB4KUYJ9OjmtI9S0UGCr80bQRSAetJK1aXbb6qEsS8eu31lB0747a5fG5GU9 6qoqgrg3aM1rPGIagmDHi0bRdxPUUA9syHBMpURfQO4rm0L9O8trafsDdjwVssyC 1NJPftbx0O2HFLzNcyrUw8X3OKlHpkUOizboXehzgqCWrpPS9VQvXwEGSQSGDGXC X36KBDP1W+8pLvm1Hw+YeWBGouFaL1FVYkNFUJb1BaoDXRYa3tPY0WE7576kHSqd 3BdHBvMBGDDBN++TV1n3mTutufaAH4uqr9IXRupYSJnofBi+oxjfePbOZoXRti96 nM86zevzm19fe1ZZ1ZhFTWFNov4Om2nfaBw6FkNBoRjml62PPyc= =UHHc -----END PGP SIGNATURE----- --xHFwDpU9dbj6ez1V--