[U-Boot] [PATCH v4 15/20] sunxi: defconfig: add supported DT list for Pine64

[Andre Przywara]

Hi,

On 05/05/17 20:55, Jagan Teki wrote:
> On Wed, Apr 26, 2017 at 6:02 AM, Andre Przywara <andre.przywara at arm.com> wrote:
>> When a board uses a FIT image to load U-Boot proper, it requires a list
>> of supported device trees to be supplied in CONFIG_OF_LIST, from which it
>> chooses the right one at runtime.
>> For boards with just one possible DT (like the OrangePi PC2) this
>> defaults to CONFIG_DEFAULT_DEVICE_TREE, but for the Pine64 with its two
>> possible models we provide all compatible DTs in this config symbol.
>>
>> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
>> ---
>>  configs/pine64_plus_defconfig | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/configs/pine64_plus_defconfig b/configs/pine64_plus_defconfig
>> index 92bda60..593e24a 100644
>> --- a/configs/pine64_plus_defconfig
>> +++ b/configs/pine64_plus_defconfig
>> @@ -3,6 +3,7 @@ CONFIG_ARCH_SUNXI=y
>>  CONFIG_MACH_SUN50I=y
>>  CONFIG_RESERVE_ALLWINNER_BOOT0_HEADER=y
>>  CONFIG_DEFAULT_DEVICE_TREE="sun50i-a64-pine64-plus"
>> +CONFIG_OF_LIST="sun50i-a64-pine64 sun50i-a64-pine64-plus"
> 
> fdtfile env is compile option now, so it all ways assign
> CONFIG_DEFAULT_DEVICE_TREE so it can't pick sun50i-a64-pine64.dtb
> here, are you manage this in runtime board code?

There may be a confusion about two different uses of DT:
CONFIG_DEFAULT_DEVICE_TREE and CONFIG_OF_LIST are there to tell which DT
U-Boot (proper) *itself* uses: and yes, we pick one of OF_LIST at
runtime (based on some board-specific code, for instance 512MB RAM on
the Pine64(non-plus).
The "fdtfile" environment variable is to give a filename stub for
loading an *external* DT for the *OS*.
Eventually we hopefully won't need that variable and .dtb loading at
all, instead we just pass U-Boot's DT ($fdtcontroladdr) on the OS. This
removes the churn distributions have these days with having to provide
.dtb files for each and every board they want to support.

Cheers,
Andre.