[U-Boot] [PATCH] arm64: allwinner: a64: Disable ehci1 and ohci1 for bananapi, nanopi

[Andre Przywara]

Hi,

On 04/07/18 01:50, Vasily Khoruzhick wrote:
> On Tue, Jul 3, 2018 at 5:45 PM, André Przywara <andre.przywara at arm.com> wrote:
> 
>>>
>>> I tried enabling DM for MMC on A64 recently and unfortunately it results in
>>> SPL exceeding 32kb size limit.
>>
>> Mmh, worked for me with this preliminary branch:
>> [1] https://github.com/apritzel/u-boot/commits/sunxi-dm-WIP
>> (which I forgot to link in my original email).
>> Did you enable SPL_DM_MMC or SPL_DM as well? I think there is not much
>> benefit in doing so, especially given the code size issue.
> 
> Yes, I did. We'll need it to handle all the controller quirks
> eventually (new clock mode, calibration, delays).
> Currently we have a number of ifdefs in the driver.

Yes, and they somewhat have to stay because of that, and we might have
to add some more, even. That's admittedly not pretty, and we were
discussing that already (the other thread that Jagan pointed you to).
But for the SPL specifically we just need some basic functionality to
load 600KB or so of data.
Or did you experience any problems with that? In general I think we can
get away with less performance for the sake of a simpler driver. For
instance I believe we will probably never need support for HS modes.

So yes: the usefulness of the DM_MMC conversion is somewhat questionable
because of this. As you have shown below ("overflowed by 10K") DM_MMC is
not really an option for the SPL, so we need to keep the old code
around. Or we follow the idea of having a much simpler, separate driver
just for the SPL.

>>> So I guess we'll have to find a workaround for this issue as well...
>>
>> I recently made a patch that shrinks the ARMv8 exception table code by
>> 250 bytes. Not much, but might help. How much did you overflow?
>> I think eventually we should generate the exception table and put it
>> somewhere else than in SRAM A1. That has the potential of freeing up
>> about 2KB or so. I started rewriting the vectors to make this easier,
>> but it's not very high on my TODO list.
> 
> That won't be enough:
> 
> aarch64-linux-gnu-ld.bfd: region `.sram' overflowed by 10584 bytes

Well, I don't see a way of achieving this, really. I think adding
SPL_DM_MMC would even overflow a 32-bit (Thumb2) SPL. And I am not sure
that adding a TPL is the right answer to this problem of using the
driver model. It's a boot loader, after all.

Cheers,
Andre.