Applying DTB Overlays from ATF on RZ/G2

[Adam Ford]

On Tue, Jan 10, 2023 at 7:40 AM Marek Vasut <marex at denx.de> wrote:
>
> On 1/10/23 14:19, Adam Ford wrote:
> > On Tue, Jan 10, 2023 at 7:02 AM Marek Vasut <marex at denx.de> wrote:
> >>
> >> On 1/7/23 13:01, Adam Ford wrote:
> >>> On Wed, Jan 4, 2023 at 5:55 PM Marek Vasut <marex at denx.de> wrote:
> >>>>
> >>>> On 1/5/23 00:48, Heinrich Schuchardt wrote:
> >>>>> Am 5. Januar 2023 00:19:36 MEZ schrieb Adam Ford <aford173 at gmail.com>:
> >>>>>> On Wed, Jan 4, 2023 at 5:15 PM Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> >>>>>>>
> >>>>>>> On 1/4/23 22:35, Adam Ford wrote:
> >>>>>>>> ATF generates a couple memory nodes based on how it's compiled and
> >>>>>>>> generates a reserved-memory node, and I want to overlay it with the
> >>>>>>>> device tree so Linux knows about this reserved memory.
> >>>>>>>>
> >>>>>>>> When I boot U-Boot, I can read the reserved-memory node:
> >>>>>>>>
> >>>>>>>> => fdt addr 0xe631e588
> >>>>>>>> Working FDT set to e631e588
> >>>>>>>> => fdt print /reserved-memory
> >>>>>>>> reserved-memory {
> >>>>>>>> lossy-decompression at 54000000 {
> >>>>>>>> renesas,formats = <0x00000000>;
> >>>>>>>> no-map;
> >>>>>>>> reg = <0x00000000 0x54000000 0x00000000 0x03000000>;
> >>>>>>>> compatible = "renesas,lossy-decompression", "shared-dma-pool";
> >>>>>>>> };
> >>>>>>>> };
> >>>>>>>> =>
> >>>>>>>>
> >>>>>>>> I attempt to overlay it with the following:
> >>>>>>>>
> >>>>>>>> => run loadfdt
> >>>>>>>> 65932 bytes read in 6 ms (10.5 MiB/s)
> >>>>>>>> => fdt addr $load_addr
> >>>>>>>
> >>>>>>> When actually setting the address you will see a message "Working FDT
> >>>>>>> set to %lx\n". So I assume $load_addr is empty.
> >>>>>>>
> >>>>>>> Did you mean $loadaddr or $fileaddr?
> >>>>>>
> >>>>>> Opps, that was a copy-paste error.  Even with that, I still get the
> >>>>>> failure to overlay:
> >>>>>>
> >>>>>
> >>>>> Did you load a .dtbo file to apply? You cannot apply a devicetree.
> >>>>>
> >>>>> Is the fdt that you want to apply the overlay to built with symbols (dtc parameter -@)?
> >>>>
> >>>> Note that the fragment passed to U-Boot by upstream ATF is already
> >>>> automatically merged into the U-Boot control DT (see
> >>>> board/renesas/rcar-common/common.c ) . U-Boot should pass that on to
> >>>> Linux automatically.
> >>>
> >>> I ran some tests, and it appears the function fdtdec_board_setup is
> >>> never getting called.  That looks like the code that grabs the blob
> >>> from ATF.  I intentionally removed the memory nodes from the kernel
> >>> device tree expecting the memory nodes to get added from ATF, but when
> >>> I booted it, it promptly hung.  That implied to me that the memory
> >>> nodes didn't get added from ATF.
> >>>
> >>> I added some debug code and noticed that ft_board_setup did not get
> >>> executed, so I created a call to fdtdec_board_setup from
> >>> ft_board_setup and my board booted just fine.  I am curious to know if
> >>> other rcar/rzg2 boards are seeing something similar?  Is calling
> >>> fdtdec_board_setup from ft_board_setup appropriate?
> >>
> >> Note that fdtdec_board_setup() is called very early on when U-Boot
> >> itself starts up and it is used to patch the fragment passed from ATF
> >> into U-Boot control DT. The ft_board_setup() is called before booting
> >> OS, i.e. at much later stage.
> >>
> >> Can you maybe summarize what exactly it is that you're trying to pass
> >> through , and from where to where ?
> >
> > There is a reserved-memory node generated by ATF and I want to pass
> > that node to the Linux Kernel, so the memory is reserved, because
> > accessing the memory will cause Linux to crash.  I wanted to put the
> > reserved-memory node into the kernel dts file, but Geert asked me to
> > pass the blob from ATF instead of hard-coding it into the dts.
> > I am just trying to figure out how to make that happen, because it
> > appears the memory isn't being reserved.
>
> So, can you check whether the U-Boot control DT does contain this
> reserved memory node ?
>
> => fdt addr $fdtcontroladdr
> => fdt print /path/to/the/node
>
=> fdt addr $fdtcontroladdr
Working FDT set to bbedccb0
=> fdt print /reserved-memory
reserved-memory {
lossy-decompression at 54000000 {
compatible = "renesas,lossy-decompression", "shared-dma-pool";
reg = <0x00000000 0x54000000 0x00000000 0x03000000>;
no-map;
renesas,formats = <0x00000000>;
};
};
=>

So it does appear that the reserved-memory is showing up here.

Is there a way to export just this node and append it to the kernel's DTB?

adam


> ?
>
> If so, then it is up to U-Boot to pass its own reserved memory nodes
> onward to Linux.