From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Simek Date: Tue, 3 Mar 2020 07:52:04 +0100 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 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. Thanks, Michal