[U-Boot] [PATCH PATCH v4 00/15] Add support for applications of overlays in SPL

Wed Sep 11 13:39:34 UTC 2019

Hi Simon,

On 13/08/2019 11:33, Simon Glass wrote:
> Hi Jean-Jacques,
>
> On Mon, 5 Aug 2019 at 03:44, Jean-Jacques Hiblot <jjhiblot at ti.com> wrote:
>>
>> The purpose of this series is to provide the SPL with ability to apply
>> overlays for u-boot. this is only a RFC so far, to get a feedback on the
>> approach.
>>
>> Our use-case is the support of the daughter boards of the AM65x EVM. In
>> Linux, each board is supported by a unique overlay. The presence of the
>> boards is detected at runtime, and some useful features (like USB) are
>> implemented on those daughter boards. Instead of providing multiple dtbs
>> and fall in a combinatorial pit, we propose to use DT overlays.
> But why do this in SPL? Is it so U-Boot can use the DT with overlays
> itself for driver model?

Sorry for the long delay.

You are right, the goal is to be able to apply DTB overlays in the SPL 
so that u-boot the DTB+ overlays for its driver model.

Our platform for example has optional daughter cards with various 
combination of PCIe, USB and Ethernet.

At the kernel level the hardware is described in separate overlays. 
U-boot is responsible to detect the HW and load/apply the needed overlays.

We want to do the same in u-boot and the SPL will load/apply the right 
overlays.

JJ

>
>> Patch #2 "spl: fit: Add support for applying DT overlay" has been posted
>> a few weeks ago by Michal Simek.
>> Patch #3 to #6 amend Michal's patch.
>> Patch #7 to #9 are simple fixes for the Makefile
>> Patch #10 is used to reduce the complexity of the Makefile by having FIT
>> generator scripts provide their dependencies
>> Patch #12-#13 allow to use the board driver in SPL
>> Patch #14-#15 adds a way to dynamically select the DT overlays. That is
>> were we would use HW detection to select the required overlays. In that
>> case, the board driver code tells what overlay it needs (it gives the
>> name of the node).
>>
>> On arm, if overlay are supported, this series increases the size of the SPL
>> by 3.2 kB.
>>
>> Travis build : https://travis-ci.org/jjhiblot/u-boot/builds/567779404
>>
>> Changes in v4:
>> - use CONFIG_IS_ENABLED() instead of #idef
>> - make sure that the temp buffer is freed in all cases
>> - Use the board driver infrastructure to get the image names from the
>> board code.
>> - Remove a patch that passed the board name to the FIT generator. If needed
>> the generator can get it from elsewhere
>> - Add a fix to not load the firmware twice (once as a firmware and once as
>> a loadable)
>>
>> Changes in v3:
>> - Add a new config option: SPL_LOAD_FIT_APPLY_OVERLAY. By default, it is
>> not selected.
>> - removed the RFC prefix. This work will be needed soon by TI's AM65x
>> platform. and can probably benefit other modular platforms
>> - removed the last patch that provided an example of how to use this with
>> on a DRA76.
>> - removed the patch that made u-boot.img a symlink to u-boot.itb because
>> it breaks the build of many platforms (because files required to build the
>> ITB are missing)
>> - removed the patch to reduce the footprint of the am335x SPL. (already
>> merged)
>> - Made the boot flow more permissive (don't fail immediately if an overlay
>> is not present) and more verbose when an error occures
>> - handle the dependencies of the FIT generation in a more generic way
>> - use a dedicated kconfig option to enable the application of the overlays
>> by the SPL.
>>
>> Changes in v2:
>> - reworked board_fit_get_additionnal_images() and how it used in spl_fit.c
>> - removed dtbo generation from dtso files and use .dts extension for the
>>    overlays
>> - add dynamic allocation usage in a separate patch
>> - defconfig change for the am335x_evm
>>
>> Jean-Jacques Hiblot (14):
>>    spl: fit: don't load the firmware twice
>>    spl: fit: Make room in the FDT before applying overlays
>>    spl: fit: allocate a temporary buffer to load the overlays
>>    spl: fit: Do not fail immediately if an overlay is not available
>>    spl: fit: be more verbose when an error occurs when applying the
>>      overlays
>>    Makefile.lib: include /__symbols__ in dtb if
>>      SPL_LOAD_FIT_APPLY_OVERLAY is enabled
>>    Makefile: Fix tests for CONFIG_SPL_LOAD_FIT and
>>      CONFIG_SPL_FIT_GENERATOR
>>    Makefile: Fix u-boot.itb generation when building outside the source
>>      tree
>>    Makefile: Query the SPL Fit Generator for its dependencies
>>    spl: fit: constify the output parameter of spl_fit_get_image_name()
>>    drivers: board: Make the board drivers available in SPL
>>    drivers: board: Add get_fit_loadable()
>>    include: board: provide empty stubs when the BOARD option is not
>>      selected
>>    spl: fit: Allow the board to tell if more images must be loaded from
>>      FIT
>>
>> Michal Simek (1):
>>    spl: fit: Add support for applying DT overlay
>>
>>   Kconfig                                       |   9 ++
>>   Makefile                                      |  23 ++--
>>   arch/arm/mach-imx/mkimage_fit_atf.sh          |   5 +
>>   arch/arm/mach-rockchip/make_fit_atf.py        |   7 ++
>>   board/sunxi/mksunxi_fit_atf.sh                |   4 +
>>   .../lion_rk3368/fit_spl_atf.its               |   6 +-
>>   .../puma_rk3399/fit_spl_atf.sh                |   6 +
>>   common/spl/spl_fit.c                          | 104 ++++++++++++++++--
>>   drivers/Makefile                              |   2 +-
>>   drivers/board/Kconfig                         |   2 +
>>   drivers/board/Makefile                        |   2 +-
>>   drivers/board/board-uclass.c                  |  11 ++
>>   include/board.h                               |  72 ++++++++++++
>>   scripts/Makefile.lib                          |   4 +
>>   14 files changed, 230 insertions(+), 27 deletions(-)
>>
>> --
>> 2.17.1
>>
> Please can we have a sandbox test for this?
>
> Regards,
> SImon
>