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

[Atish Patra]

On Tue, Nov 3, 2020 at 10:28 AM Ben Dooks <ben.dooks at codethink.co.uk> wrote:
>
> On 03/11/2020 18:10, Cyril.Jean at microchip.com wrote:
> > On 11/3/20 3:07 PM, Atish Patra wrote:
> >> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> >>
> >> 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.
>

I use tftpboot to load the kernel & DT from the network. SD card is
enabled in this DT and Linux
kernel uses SD slot instead of eMMC.

To summarize, eMMC is used for HSS & U-Boot while SD card is used for
Linux which makes
more storage available to Linux.

IMO, we should enable the sdcard for Linux DT until updated FPGA
design & HSS is available.

> --
> Ben Dooks                               http://www.codethink.co.uk/
> Senior Engineer                         Codethink - Providing Genius
>
> https://www.codethink.co.uk/privacy.html



-- 
Regards,
Atish