[RFC PATCH 2/3] RISC-V: Initial DTS for Microchip ICICLE board

[Cyril.Jean at microchip.com]

On 11/3/20 6:28 PM, Ben Dooks wrote:
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> On 03/11/2020 18:10, Cyril.Jean at microchip.com wrote:
>> On 11/3/20 3:07 PM, Atish Patra wrote:
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>>> On Fri, Oct 30, 2020 at 2:20 PM Ben Dooks 
>>> <ben.dooks at codethink.co.uk> wrote:
>
> ,snip[
>
>>>>> @Cyril : Can we enable both eMMC & sdcard at the same time ?
>>>> I would put /both/ in but only enable the one in use for the moment.
>>>> Our boards are booting of eMMC as supplied, so this isn't going to 
>>>> work
>>>> as well. The eMMC is 8bit wide, and thus is only delivering 11MB/sec
>>>> instead of 22MB/sec. This performance is still not great, but losing
>>>> half the data-rate is just not good.
>>>>
>>> I am not sure what should be enabled by default. Updating sdcard is 
>>> much
>>> easier than eMMC card and we use that approach.
>>>
>>> @Cyril: Is there a way that we can enable both ?
>>>
>> Yes, we can enable both but this requires a modification to the FPGA
>> design. One of the guys prototyped this while I was away. We will move
>> this along. This will require reprogramming the FPGA with a new design
>> and HSS version.
>>
>> Regards,
>>
>> Cyril.
>
> I either missed or couldn't find a way of forcing the boot mode to be
> from the SD slot. Have I missed something? At the moment we'd like to
> have more storage available as the ~7G free on the eMMC is not enough.
>
Currently, you need to program a different FPGA bitstream on  the board 
to boot from SD-card. The different bitstream configures muxes on the 
board to connect the SD slot to the FPGA and the HSS included in the bit 
stream configures the FPGA IOs correctly.

Links to the programming files are found in this document: 
https://github.com/polarfire-soc/polarfire-soc-documentation/blob/master/boards/mpfs-icicle-kit-es/updating-icicle-kit/updating-icicle-kit-design-and-linux.md


Regards,

Cyril.