On 4/11/19 2:12 PM, Paul Walmsley wrote:
On Thu, 11 Apr 2019, Christoph Hellwig wrote:
On Thu, Apr 11, 2019 at 01:42:59AM -0700, Paul Walmsley wrote:
Similar to ARM64, add support for building DTB files from DT source
data for RISC-V boards.
This patch starts with the infrastructure needed for SiFive boards.
Boards from other vendors would add support here in a similar form.
What do we build it for? We'd really need something like this:
http://git.infradead.org/users/hch/misc.git/commitdiff/d6242aa147baf57e05e2932199c74d8d24b9926e
http://git.infradead.org/users/hch/misc.git/commitdiff/0cd5413c8094ab57b68e0629dacfed695f4c1ef1
To actually use the DT files.
Those patches might be useful - I have not reviewed them closely - but
they are not necessary.
The FSBL already supplies a DTB to Linux. I assume the U-boot port works
the same way.
I am bit confused here. I thought the idea behind putting the the DTS in
kernel so that Kernel don't need to depend on DT passed from boot
loaders. Currently, DTB passed from FSBL is modified by OpenSBI/BBL
before passing to U-Boot or Linux.
If Linux kernel can boot from the DTS contained within its source code
as is, that would be much more helpful.
I haven't switched to U-boot yet for these driver tests, so I personally
have been using the open-source FSBL (freedom-u540-c000-bootloader) with
the following trivial patches applied:
https://github.com/sifive/freedom-u540-c000-bootloader/tree/dev/paulw/supply-fsbl-dtb-v5.1-rc4
The fsbl/ux00_fsbl.dtb file can be symlinked to the kernel DTB output,
e.g., ~/linux/arch/riscv/boot/dts/sifive/hifive-unleashed-a00-fu540.dtb.
This assumes that FSBL has to be rebuilt every time I want to change the
DT. I was hoping to avoid that.
Regards,
Atish
- Paul
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