Hi Marek,
On 6/28/24 4:42 AM, Marek Vasut wrote:
On 6/27/24 2:42 PM, Quentin Schulz wrote:
Hi Marek,
Hi,
On 6/27/24 1:58 AM, Marek Vasut wrote:
Insert /u-boot,<dto-name> = <index> property into the U-Boot control DT
during SPL DTO application process. This can be used by user to inspect
which DTOs got applied by the SPL and in which order from running
U-Boot.
Example:
```
u-boot=> fdt addr $fdtcontroladdr && fdt list /
Working FDT set to aee9aeb0
/ {
u-boot,fdt-dto-imx8mp-dhcom-pdk3-overlay-rev100 = <0x00000005>;
u-boot,fdt-dto-imx8mp-dhcom-som-overlay-rev100 = <0x00000004>;
u-boot,fdt-dto-imx8mp-dhcom-pdk-overlay-eth2xfast =
<0x00000003>;
u-boot,fdt-dto-imx8mp-dhcom-som-overlay-eth2xfast =
<0x00000002>;
...
```
Shouldn't this rather be in /config node?
This is what I had there originally, but then I realized that some DTs
might not have the /config node in them (or am I mistaken?), so I moved
the new properties into the root node, which surely exists.
It also keeps the code simpler, as it doesn't have to fiddle with
creation of the /config node if it doesn't exist.
I don't think we should pollute the root node with this. If we want to
be able to expose this in a proper binding to the upstream DT binding
repo, I'm not sure this is going to fly :/
Also, I am highly suggesting to have an additional prefix aside from
u-boot to avoid unfortunate name clashes between DTO and existing
properties.
OK, fixed in V2.
Or could be in its own child node of /config ?
Please see above.
In any case, can you please add or edit a file somewhere to define
this new dt-binding.
Done in V2
Additional question, what is this index for?
To indicate in which order the DTOs were applied by the SPL. It matches
the order in which the the DTOs are stored in the fitImage and the order
in which SPL iterates over them. In case the SPL skips a DTO using
board_spl_fit_append_fdt_skip(), the integer sequence might have gaps.
I am wondering if we cannot simply have a string array with overlays
applied left-to-right or right-to-left instead? Or u-boot,fdt-dto-N =
"imx8mp-dhcom-pdk3-overlay-rev100";
We can, but that is much harder to test for presence of specific DTO on
U-Boot command line. It is easy to test for presence of boolean or
integer DT property using 'fdt' command.
Not sure dt-bindings people would love to hear that we adapt the fdt to
be easier to work with from the U-Boot CLI :)
In any case, another few thoughts that popped up overnight:
1- do we want to have this for SPL DTB modified by TPL? If so, I'm sure
we want it different from the one passed from SPL to U-Boot proper IFF
we start from a clean sheet (new DTB) and/or add the DTBO we applied on
top the DTBOs already applied by the TPL to the SPL DTB before passing
it to proper
2- Add info about which DTBOs were applied to the kernel DTB?
Cheers,
Quentin
