Applying DTB Overlays from ATF on RZ/G2

[Adam Ford]

On Mon, Jan 9, 2023 at 2:46 AM Biju Das <biju.das.jz at bp.renesas.com> wrote:
>
> Hi Adam,
>
> > Subject: Re: Applying DTB Overlays from ATF on RZ/G2
> >
> > On Sat, Jan 7, 2023 at 6:01 AM Adam Ford <aford173 at gmail.com> 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"; }; }; =>
> > > > >>>>
> >
> > + CC Biju Das
>
> > > > >>>> 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.
>
> Without that board detection and proper memory detection in u-boot/kernel won't happen.
> [1] https://elixir.bootlin.com/u-boot/latest/source/board/hoperun/hihope-rzg2/hihope-rzg2.c#L83
>

Right now, my device trees have the memory node(s), but not the
reserved-memory node which I'm trying to insert dymanically based on
how ATF is built.

>
> > > 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?
>
> It should be working as we are using lossy compression for media playback for VLP release
> and VLP release[1] is using Mainline ATF and U-boot. Similar case for R-Car.
> I remember correctly for lossy compression case, we explicitly add a node in kernel [2].
>
> [1] https://github.com/renesas-rz/rz_linux-cip/blob/rz-5.10-cip17/arch/arm64/boot/dts/renesas/r8a774b1-hihope-rzg2n.dts#L27
>
> [2] https://github.com/renesas-rcar/linux-bsp/blob/v5.10.41/rcar-5.1.3.rc10/arch/arm64/boot/dts/renesas/r8a77961-salvator-xs.dts#L32
>

Your custom repo has the reserved-memory node in the device tree.  I
was trying to figure out how to get the reserved-memory node to
propagate from ATF through U-Boot to Linux without needing to have the
reserved-memory node in the device tree.  I had attempted to add the
reserved-memory node upstream, and Geert asked me to use ATF insead.
I added debug code into the function that reads the ATF node that is
passed to U-Boot and it doesn't appear to be getting called unless I
modify the code  to explicitly do it.  I wasn't sure if I am missing a
Kconfig option somewhere.

adam

>
> Cheers,
> Biju
>
>