[U-Boot] [PATCH 4/4] ARM: renesas: Configure DRAM size from ATF DT fragment

[Marek Vasut]

On 3/13/19 4:25 PM, Eugeniu Rosca wrote:
> On Tue, Mar 12, 2019 at 10:11:21PM +0100, Marek Vasut wrote:
>> On 3/12/19 8:30 PM, Eugeniu Rosca wrote:
>>> Hi Marek cc: Michael
>>
>> Hi,
>>
>>> On Tue, Mar 5, 2019 at 4:37 AM Marek Vasut <marek.vasut at gmail.com> wrote:
>>>>
>>>> The ATF can pass additional information via the first four registers,
>>>> x0...x3. The R-Car Gen3 with mainline ATF, register x1 contains pointer
>>>> to a device tree with platform information. Parse this device tree and
>>>> extract DRAM size information from it. This is useful on systems where
>>>> the DRAM size can vary between configurations.
>>>
>>> 1. Do the ATF changes supporting this feature already exist in mainline ATF?
>>
>> Yes, for quite some time, see
>> commit 1d85c4bd5b6291b99feb2409525c96f0c1744328
>>     plat: rcar: Pass DTB with DRAM layout from BL2 to next stages
> 
> That's helpful, but I think such information should go by default into
> commit description.
> 
> [..]
> 
> Besides the above, I wonder why this patch duplicates code across three
> board files? Could this code be relocated to some common area like [1]?

That's the plan.

> FWIW building the latter could be re-enabled by reverting the Makefile
> changes from v2018.01-rc1 commit [2].

I prefer a more progressive approach, that is applying patches, rather
than reverting.

> To differentiate between the boards which expect/require the ATF args
> and those which don't, I guess that run-time (IS_ENABLED) checking of
> a newly created Kconfig symbol, e.g. SUPPORTS_ATF_ARGS or similar,
> selected on per-board basis, could do the job?

No, the code should auto-detect whether the ATF supports the DT passing
or not.

> Note that we already face the need to have an area for Android features
> common between all Gen3 boards, so I think reviving [1] is inevitable.
> 
> [1] board/renesas/rcar-common/common.c
> [2] http://git.denx.de/?p=u-boot.git;a=commitdiff;h=e23eb942ad10
>     ("ARM: rmobile: Stop using rcar-common/common.c on Gen3")
> 
> Best regards,
> Eugeniu.
> 


-- 
Best regards,
Marek Vasut