From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: [PATCH 0/7] sunxi: Add DT representation for the MBUS controller Date: Thu, 31 May 2018 14:52:27 +0200 Message-ID: <20180531125227.6c4k5glyvvqrf7fo@flea.home> References: <20180409092229.ljcnsqgv7wh2s4op@flea> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1521625459==" Return-path: In-Reply-To: <20180409092229.ljcnsqgv7wh2s4op@flea> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Rob Herring Cc: Mark Rutland , devicetree@vger.kernel.org, Thomas Petazzoni , Arnd Bergmann , Robin Murphy , dri-devel , Paul Kocialkowski , Chen-Yu Tsai , Yong Deng , Frank Rowand , Dave Martin , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" List-Id: devicetree@vger.kernel.org --===============1521625459== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="qjs6tgge4xg5dwmj" Content-Disposition: inline --qjs6tgge4xg5dwmj Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Apr 09, 2018 at 11:22:29AM +0200, Maxime Ripard wrote: > Hi Rob, >=20 > On Tue, Apr 03, 2018 at 11:03:30AM -0500, Rob Herring wrote: > > On Tue, Apr 3, 2018 at 8:29 AM, Maxime Ripard wrote: > > > Hi, > > > > > > We've had for quite some time to hack around in our drivers to take i= nto > > > account the fact that our DMA accesses are not done through the parent > > > node, but through another bus with a different mapping than the CPU f= or the > > > RAM (0 instead of 0x40000000 for most SoCs). > > > > > > After some discussion after the submission of a camera device sufferi= ng of > > > the same hacks, I've decided to put together a serie that introduce a > > > property called dma-parent that allows to express the DMA relationship > > > between a master and its bus, even if they are not direct parents in = the DT. > >=20 > > Reading thru v6 of the camera driver, it seems like having > > intermediate buses would solve the problem in your case? >=20 > I guess it would yes, but I guess it wouldn't model the hardware > properly since this seems to be really a bus only meant to do DMA, and > you're not accessing the registers of the device through that bus. >=20 > And as far as I know, the DT implies that the topology is the one of > the "control" side of the devices. >=20 > We'll also need eventually to have retrieve the MBUS endpoints ID to > be able to support perf and PM QoS properly. >=20 > > As Arnd mentioned in that thread, something new needs to address all > > the deficiencies with dma-ranges and describing DMA bus topologies. > > This doesn't address the needs of describing bus interconnects. > > There's been some efforts by the QCom folks with an interconnect > > binding. They've mostly punted (for now at least) to not describing > > the whole interconnect in DT and keeping the details in a driver. >=20 > Is it that patch serie? https://lkml.org/lkml/2018/3/9/856 >=20 > > On the flip side, this does mirror the established pattern used by > > interrupts, so maybe it's okay on it's own. I'll wait for others to > > comment. >=20 > We'll see how it turns out then :) Ping? How should we move forward on this? Maxime --=20 Maxime Ripard, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com --qjs6tgge4xg5dwmj Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEE0VqZU19dR2zEVaqr0rTAlCFNr3QFAlsP8AgACgkQ0rTAlCFN r3STIA/6ArSg8MsHYDYK8k6YLs9VK5rpghao0HU+hZMJzFgiKV3j7H/wGdV2l5fK 3k5fxnXGSsMam5zcOE1MJ74LOi1+7Xh0KLasWiVcMawio/igelYcj0mzdbpTazVP VNh/r4X2TIq17bhdRmpWOBb9nBSmod/NnUpeU4gutnZ6+XvVTTQrOQA9MKoiUh9u J4DYlTGsVDRxn0mATNWVlbF7HeBB8+Xm76co5IM0i375mK+W9q9zh7d6E4uRkqxV a+UJ/ym0EodVRJU5yiZ8eRcmoNB6sczUUDzThLlLWa5bIdIfGGH+bgWCSLSEASrr l9MmxPz/I1wZQQnH5K8a66XJFfQvwj09h3XVNSzKTAEWo9/dXBCu/G6aExDy0en8 BowmSRaGf9VBhNlX/yB/zjcVNzuul3IcDSrmMIQ7Vw4m5yJOuqxTWAP4ojdLHQ5X UbvMv9321rMHcL7z80oscSwSj9lO0VipIGtYZkZ3c0RivTqSlk1eP8DMgUaXsuBi yNOxkddadShpeC2TScakiBTy6w7O2dnJ/Rvn3DYQSwTF84oI+V3vaCvzvRTfKvno ntgrwVWFPCI3Q5sm4SDHq4PLJrcb4WmXrXuXe+2OWHehf4YikStpC6NvSmwD7RR4 C8UXixadehk02qGNfi+KNzfYYO5vHUVxqN4oGUr711a/TaTfJDo= =E4nN -----END PGP SIGNATURE----- --qjs6tgge4xg5dwmj-- --===============1521625459== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KZHJpLWRldmVs IG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8vbGlz dHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vZHJpLWRldmVsCg== --===============1521625459==--