[U-Boot] [PATCH 3/3] rockchip: fix incorrect detection of ram size

[Dr. Philipp Tomsich]

Marty,

> On 19 May 2018, at 12:40, Marty E. Plummer <hanetzer at startmail.com> wrote:
> 
> On Mon, May 14, 2018 at 05:56:27PM +0200, Dr. Philipp Tomsich wrote:
>> I had a bit more time to look into this and it looks as if we have two problem-spots...
>> 
>> First, there's a type-mismatch between ram_info.size (a size_t) and gd.ram_size (phys_size_t).
>> While we can increase the size of a phys_size_t to 64bit (by defining CONFIG_PHYS_64BIT),
>> the size_t will always be an unsigned int on a 32bit arm architecture.  So here's one possible
>> pitfall that should be resolved.
>> 
>> Once this is adjusted, we might just increase the width of ram_info.size to 64bit by enabling
>> CONFIG_PHYS_64BIT ... however, this comes with a caveat: the default cell sizes for the
>> FDT (via fdtdec) also increases.  I.e. if any come in our arch or the drivers still goes through
>> the fdtdec-functions, we'll end up with a problem.
>> 
>> As my test coverage is limited to 64bit targets, I can't tell whether defining the PHYS_64BIT
>> configuration would be possible for the RK3288 -- if it is, we'd have a rather easy way forward
>> and could reuse the phys_size_t for ram_info.size.
>> 
>> I'd appreciate if you could take a look at whether CONFIG_PHYS_64BIT gets us into a lot
>> of trouble on the RK3288 or whether this will trigger just a few minor adjustments...
>> 
>> Thanks,
>> Philipp.
> 
> So explain to me what you'd like me to do here, if you would. What I
> gather from this is you want me to flip CONFIG_PHYS_64BIT and see if it
> works or what? I can flash/reflash u-boot and coreboot pretty easily on
> the device, so I'm down for any sort of hardware testing needed to get
> this into a usable state.

Yes, just enable PHYS_64BIT and report on how far it goes (activating some
debug may be helpful to understand what goes wrong, if it fails).

My gut feeling is that it could work, but there’s a number of pitfalls and we may
not be lucky.

Regards,
Philipp.