Re: [RFC PATCH v2 1/4] dt-bindings: misc: Add bindings for misc. BMC control fields

[Alexander Amelkin <a.amelkin@yadro.com>]

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20.07.2018 03:07, Andrew Jeffery wrote:
>> Andrew, can you start with a list that shows what you expect us to need
>> on our systems ?
>>
> Okay, our Witherspoon and Romulus platforms containing the ASPEED AST2500 currently need the following tuneables exposed:
>
> From the SCU:
> - Debug UART enable
> - VGA DAC mux
> - VGA scratch registers 0-7
> - LPC SuperIO decode enable
> - VGA MMIO decode enable
>
> From the LPC controller:
> - iLPC2AHB enable
> - SuperIO scratch registers 0x20-0x2f
>
> (The LPC controller is just as much of a collection of random bits as the SCU)
>
> Lastly, our Palmetto platform uses an AST2400 which has fewer features compared to the AST2500. Its tuneable list is the same as the above with the exception of "Debug UART enable".
>
> Tuneables that we may need to expose in the future include:
>
> From the SCU:
> - PCI VID/DID for the BMC PCIe device
> - VGA device enable (may need to be disabled if the platform contains a discrete graphics processor)
>
> From the LPC controller:
> - UART mux
>
> Alexander, Eugene, can you chime in with your platforms' needs?
In addition to what you've mentioned, we also need (and I believe you need it too) the SCU3C register (reset control/status) to determine the BMC reset reason and only perform certain actions on cold boots (see https://github.com/openbmc/openbmc/issues/3031). Although, this could probably be handled by a separate driver, don't know which though.

Alexander.


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