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[2603:6081:7b01:cbda:2ef0:5dff:fedb:a8ba]) by smtp.gmail.com with ESMTPSA id c10-20020ac87dca000000b002e1db1b7b10sm29466995qte.25.2022.04.13.09.46.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Apr 2022 09:46:10 -0700 (PDT) Date: Wed, 13 Apr 2022 12:46:07 -0400 From: Tom Rini To: Abdellatif El Khlifi Cc: Rob Herring , ilias.apalodimas@linaro.org, achin.gupta@arm.com, sudeep.holla@arm.com, sjg@chromium.org, rui.silva@linaro.org, vishnu.banavath@arm.com, xueliang.zhong@arm.com, u-boot@lists.denx.de, nd@arm.com Subject: Re: [PATCH 0/6] introduce Arm FF-A support Message-ID: <20220413164607.GU14282@bill-the-cat> References: <20220329151659.16894-1-abdellatif.elkhlifi@arm.com> <20220406194711.GN14282@bill-the-cat> <20220407125424.GA32742@e121910.cambridge.arm.com> <20220407125811.GO14282@bill-the-cat> <20220412114315.GA18372@e121910.cambridge.arm.com> <20220412120106.GH14282@bill-the-cat> <20220413142023.GA23999@e121910.cambridge.arm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="FjrbnUlHuGeYXDPm" Content-Disposition: inline In-Reply-To: <20220413142023.GA23999@e121910.cambridge.arm.com> X-Clacks-Overhead: GNU Terry Pratchett X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.39 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" X-Virus-Scanned: clamav-milter 0.103.5 at phobos.denx.de X-Virus-Status: Clean --FjrbnUlHuGeYXDPm Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Apr 13, 2022 at 03:20:23PM +0100, Abdellatif El Khlifi wrote: > On Tue, Apr 12, 2022 at 08:28:42AM -0500, Rob Herring wrote: > > On Tue, Apr 12, 2022 at 7:01 AM Tom Rini wrote: > > > > > > On Tue, Apr 12, 2022 at 12:43:15PM +0100, Abdellatif El Khlifi wrote: > > > > On Thu, Apr 07, 2022 at 08:58:11AM -0400, Tom Rini wrote: > > > > > On Thu, Apr 07, 2022 at 01:54:24PM +0100, Abdellatif El Khlifi wr= ote: > > > > > > On Wed, Apr 06, 2022 at 03:47:11PM -0400, Tom Rini wrote: > > > > > > > On Tue, Mar 29, 2022 at 04:16:53PM +0100, abdellatif.elkhlifi= @arm.com wrote: > > > > > > > > From: Abdellatif El Khlifi > > > > > > > > > > > > > > > > This patchset adds support for Arm FF-A (Arm Firmware Frame= work for Armv8-A v1.0). > > > > > > > > > > > > > > > > FF-A support is generic by design and can be used by any Ar= m platform. > > > > > > > > > > > > > > > > The features added are as follows: > > > > > > > > > > > > > > > > 1/ FF-A device driver > > > > > > > > 2/ armffa command > > > > > > > > 3/ FF-A Sandbox driver > > > > > > > > 4/ FF-A Sandbox test cases > > > > > > > > 5/ FF-A MM communication > > > > > > > > > > > > > > > > > > > > > > > > The suggested design sees FF-A as a data bus allowing data = exchange with the firmware > > > > > > > > running under TrustZone HW (such as Optee). The same approa= ch was followed in the > > > > > > > > FF-A driver in Linux kernel (https://git.kernel.org/pub/scm= /linux/kernel/git/torvalds/linux.git/tree/drivers/firmware/arm_ffa/bus.c?h= =3Dv5.15#n211)) > > > > > > > > > > > > > > > > u-boot boards using FF-A can provide a device tree node in = a -u-boot.dtsi file. > > > > > > > > Since the node can not be hosted in Linux device tree, we s= uggest using u-boot device tree. > > > > > > > > > > > > > > Why can't the node be in the upstream tree? It should be, so= that it > > > > > > > can be shared between all users. Especially since there's in= -Linux > > > > > > > users? > > > > > > > > > > > > > > -- > > > > > > > Tom > > > > > > > > > > > > Linux already has an FF-A bus driver and doesn't use a device t= ree node for FF-A. > > > > > > > > > > > > The Linux driver registers FF-A as a bus: > > > > > > > > > > > > int arm_ffa_bus_init(void) > > > > > > { > > > > > > return bus_register(&ffa_bus_type); > > > > > > } > > > > > > > > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.= git/tree/drivers/firmware/arm_ffa/bus.c?h=3Dv5.15#n211 > > > > > > > > > > > > So, there is no user for the node in Linux. That's why we sugge= st hosting the node in the u-boot device tree (a u-boot.dtsi file) > > > > > > > > > > OK, but you can still push it upstream as it's not required to ha= ve an > > > > > in tree user. > > > > > > > > During the review of Corstone-1000 patchset, Rui Silva had a discus= sion with the Linux device tree maintainer > > > > (Rob Herring). Rob is not in favour of an FFA node in the kernel de= vice tree. This is why we are including the FFA node > > > > in u-boot device tree (u-boot.dtsi files). > >=20 > > Sigh. There is not a 'kernel device tree' and a 'u-boot device tree'. > > There is only 1. For SystemReadyIR compliance, that is a hard > > requirement. > >=20 > > > I'm a bit confused now, can you please link to the kernel thread? Or > > > Rob, can you chime in here please? > >=20 > > The FFA DT binding was rejected in favor of making FFA discoverable. > > The FFA spec was amended to address that. DT is only for what we > > failed to make discoverable. For hardware, we're stuck with it. We > > shouldn't repeat that for software interfaces. > >=20 > > Rob >=20 > Guys, >=20 > Since we can not add an FFA node in the device tree, we will make FFA a d= iscoverable bus. > So, we will manually create the udevice, binding it to the driver and pro= bing it. > Manually means directly calling device_bind and device_probe APIs. >=20 > Any thoughts about this approach ? How is it both discoverable and doesn't have a device tree node, in the kernel? --=20 Tom --FjrbnUlHuGeYXDPm Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQGzBAABCgAdFiEEGjx/cOCPqxcHgJu/FHw5/5Y0tywFAmJW/kkACgkQFHw5/5Y0 tyzNmgv/fdcaK3DVd3gh5sOUfi8rYhjHyJHzKwf2cQlW78aqsGNRqo/ptVlbjK05 9Km9qwBmQw5bEepoEVke+d3ZTGlKWCANnRw8wFgEYrYQBec5a6P7cJj/AqKe/zvL u7RTgUmUFL7xQdNXGqpeqdtvGGYOlU6ZPS5+usiRmqGvE3mWxpFuP1Hnyd9Ryauv z0Aogwk6LsUnBzdWz4j0vLMb8N+BVaRnQK1v2p/xAUTvAZhoGEHphWune4NU+sBM DMn8iLyblKN6SCE0L0HB4hdADI47XTRiZC8LAytZ38PEhsW5fotgV9iLhmp9RkNo uckmRdEx09gNCTnkkEhFcgHXl4jthoT/X0/huup/b/tu0w1V4ihIbWHO0nLbz1EU ug2Oq0X0XsCqGeegZet2tQ/qXq1Rcpio3uMWzfOWRgMYly/C7lMo5rMIv0h94lFN ixoptMUWXOka3YT6fIR9hdD8TmoiYx4H3N13cKQtB1QoOHO+55rtxESlielOz7eG 3grjPzHc =prPs -----END PGP SIGNATURE----- --FjrbnUlHuGeYXDPm--