From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Glass Date: Tue, 3 Mar 2020 19:47:54 -0700 Subject: [PATCH 1/2] Makefile: Add environment variable DEVICE_TREE to header In-Reply-To: References: <65fe3fb4b7f682b4a292b261f0140b1f89f4610e.1582041753.git.michal.simek@xilinx.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Michal, On Mon, 2 Mar 2020 at 23:52, Michal Simek wrote: > > On 02. 03. 20 20:47, Simon Glass wrote: > > Hi Michal, > > > > On Fri, 28 Feb 2020 at 04:03, Michal Simek wrote: > >> > >> On 26. 02. 20 16:33, Simon Glass wrote: > >>> Hi Michal, > >>> > >>> On Tue, 18 Feb 2020 at 09:02, Michal Simek wrote: > >>>> > >>>> Users have option to overwrite default device tree > >>>> (CONFIG_DEFAULT_DEVICE_TREE) via environment variable DEVICE_TREE. > >>>> > >>>> Feature has been added long time ago by commit 74de8c9a1672 > >>>> ("dts/Makefile: Build the user specified dts") for a little bit different > >>>> reason. > >>>> > >>>> But this variable can be also used for different purpose like choosing > >>>> proper configuration from FIT image in SPL. > >>>> And this is the functionality I would like to use on Xilinx Zynq devices > >>>> that current u-boot.img can be composed in the same way based on OF_LIST > >>>> and different configuration is taken based on platform specific SPL. > >>>> SPL requires low level ps7_init_gpl configuration that's why different > >>>> boards require different SPL with fixed board_fit_config_name_match(). > >>>> > >>>> Signed-off-by: Michal Simek > >>>> --- > >>>> > >>>> I have done it in this way but maybe there is any smarter way how this can > >>>> be done. Also macro name can change if you want. > >>> > >>> Can you please add a bit of documentation to doc/README.fdt-control ? > >> > >> This feature is cover by documentation in this file already. What > >> exactly do you think that should be added? > >> > > > > Then I suppose I am confused as to what this patch does. I thought it > > was allowing U-Boot to pass the DT to Linux, which wasn't previously > > supported? > > Just a note this is also not supported and would be good to have support > for it. > > The patch is putting device tree name as macro to header and I am using > this value just in zynq SPL to choose proper dtb file from u-boot.img. > > On ZynqMP generic platform I am using mkimage_fit_atf.sh script to > automatically fill default configuration. > https://gitlab.denx.de/u-boot/u-boot/blob/master/arch/arm/mach-zynqmp/mkimage_fit_atf.sh#L94 > And I didn't want to create different u-boot.img/itb for Zynq that's why > SPL has device tree built it directly in SPL. > > As I said maybe there is smarter way how to do it but this was the one I > used. > In our case SPL another way could be to put filename from ps7_init_* > files and save it as variable and use it. OK I see. So are you using OF_CONTROL for SPL? Regards, Simon