[U-Boot] [linux-sunxi] Re: [PATCH 0/3] sunxi: sun8i-emac: Update DT bindings

[Chen-Yu Tsai]

On Mon, Jan 29, 2018 at 5:58 PM, Maxime Ripard
<maxime.ripard at free-electrons.com> wrote:
> On Mon, Jan 29, 2018 at 09:44:44AM +0000, Andre Przywara wrote:
>> Hi,
>>
>> On 29/01/18 08:51, Maxime Ripard wrote:
>> > Hi,
>> >
>> > On Mon, Jan 29, 2018 at 01:15:19AM +0000, Andre Przywara wrote:
>> >> The existing sun8i-emac driver in U-Boot uses some preliminary bindings,
>> >> which matched our own DTs. Now that the Linux kernel got a driver, lets
>> >> update our probe code to handle those Linux DTs as well.
>> >> The first patch adds the missing compatible strings for the pinctrl drivers,
>> >> which is needed for using the sunxi_name_to_gpio() lookup function.
>> >> Patch 2/3 updates the pinctrl parser used in the sun8i-emac driver, to cope
>> >> with the new, generic Allwinner pinctrl bindings.
>> >> The final patch extends the probe routine in the Ethernet driver to deal
>> >> with both the old and the new bindings.
>> >
>> > Thanks for posting this
>> >
>> >> This series allows to copy in the DTs from the latest kernel. Unfortunately
>> >> right now updating the DTs for the H5 and A64 breaks the build, as the
>> >> resulting binary (which embeds the DT) gets to large and triggers our new
>> >> image size check.
>> >
>> > Sigh...
>> >
>> >> As the H5 and H3 share most of the DT, we can't just update the H3
>> >> DTs either. Hopefully we find some neat trick to work around that.
>> >
>> > Is it just because of the DT size, or because there's more code?
>>
>> My impression the code itself is always growing a tiny bit over the
>> weeks, but this time around it's really the DT update.
>> The current A64 .dtbs in U-Boot are around 8KB, mainline is at 13KB.
>> Similar for the H5: going from 9.5KB to 14.5KB.
>>
>> Since you did a pretty good job already in identifying the code hogs, I
>> couldn't find *easy* mitigations over the weekend.
>> One possible fix is to remove the second .dtb in the Pine64 case, for
>> which I sent a patch Friday night.
>
> Since the DT is fed to the C preprocessor, we could also put some
> #ifdef 0 around the nodes that are never used by U-Boot (like the
> clocks, timer, psci, dma, GIC, RTC, RSB, etc.)
>
> This should give us some room.

Another possibility is trimming the device tree of unneeded blocks,
possibly automatically by a tool. I think this was raised before?

ChenYu

>> Another thing that stuck out is the sha256 checksum. It's "default y" if
>> you have FIT. We need FIT for the SPL loader - but we don't do or need
>> the checksum there.
>> Some people do FIT loading for the kernel and initrd in U-Boot proper, I
>> suppose, but I am not sure how many depend on SHA256 checksums in their
>> images.
>
> I think there was someone (Tom?) that said that it was useful in some
> circumstances?
>
> Maxime
>
> --
> Maxime Ripard, Free Electrons
> Embedded Linux and Kernel engineering
> http://free-electrons.com
>
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