Re: [PATCH v1 04/10] ARM: tegra: Add reg property to Tegra20 EMC table device-tree nodes

[Dmitry Osipenko]

31.05.2021 12:14, Thierry Reding пишет:
> On Mon, May 10, 2021 at 11:25:54PM +0300, Dmitry Osipenko wrote:
>> The reg property is now specified for the emc-tables nodes in the Tegra20
>> device-tree binding. Add reg property to the EMC table device-tree nodes
>> of Tegra20 board device-trees in order to silence dt_binding_check warning
>> about the missing property.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
>> ---
>>  arch/arm/boot/dts/tegra20-acer-a500-picasso.dts | 4 ++++
>>  arch/arm/boot/dts/tegra20-paz00.dts             | 1 +
>>  2 files changed, 5 insertions(+)
> 
> In retrospect we should've just used "reg" in the first place rather
> than adding the custom "nvidia,ram-code". It's a bit redundant to have
> both of them with the same value. I wonder if we should deprecate the
> use of "nvidia,ram-code" and at least make the code look at the "reg"
> property first and only fall back to "nvidia,ram-code" if "reg" does
> not exist. We probably won't ever be able to get rid of the fallback
> for backwards-compatibility reasons, but at least that would make the
> intent a bit clearer.

This may be not doable. We have Asus TF101 which doesn't use RAM code
for the memory identification, instead it uses LPDDR chip info [1]. I
will send the LPDDR patches later on.

[1]
https://github.com/grate-driver/linux/blob/master/arch/arm/boot/dts/tegra20-asus-tf101.dts#L1115

The TF101 support mostly in a completed state now, we still need to try
to figure out why upstream kernel doesn't work using a stock Android
bootloader, so far bootloader replacement to u-boot is required.