[U-Boot] Marvell DDR training custom ODT configuration

[Baruch Siach <baruch@tkos.co.il>]

Hi Chris,

On Thu, Feb 28 2019, Chris Packham wrote:
> On Thu, Feb 28, 2019 at 10:45 PM Baruch Siach <baruch@tkos.co.il> wrote:
>> Currently the value of g_odt_config is hard coded in Marvell SoC
>> platform headers. Some SolidRun A388 SOMs need a custom value. These
>> SOMs use both DDR chip-selects, but ODT0 alone is connected to both
>> chips. For that to work we need to set g_odt_config to 0x30000, that is,
>> ODT0 is configured for both CS0 and CS1.
>>
>> How can we do that in a clean way so as to not interfere too much with
>> your periodic code syncs from Marvell's DDR training source tree?
>
> In terms of syncing the best approach is upstream first
> (https://github.com/MarvellEmbeddedProcessors/mv-ddr-marvell) then
> it's a non-issue. I've had some success on that front but that may
> only be because $dayjob has a commercial relationship with the SoC
> vendor and I can access their support channels. Even with that I've
> got two outstanding PRs on github that don't seem to be going anywhere
> (I have had some feedback through the support channel that the tRAS
> changes will be incorporated, no information as to when).
>
> Ideally instead of you or I having to maintain this code it would be
> great if someone from Marvell was involved (I see a similar comment on
> the recent ThunderX series).
>
> That all said, the only delta we have right now is the configurable 2T
> timing (Marvell's code forces 2T timing on for all boards). I've been
> tempted to mark that with #ifdef __U_BOOT__ to make it more obvious.
> We probably should do the same for any other changes we do end up
> making.

OK. I'll try to contact SolidRun's contacts at Marvell. Let's see how
far that goes.

Thanks,
baruch

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