Re: [PATCH] arm: mvebu: Add support for reading LD0 and LD1 eFuse

Marek Behún
2022-04-07T11:58:06Z

On Thu, 7 Apr 2022 13:53:23 +0200
Pali Rohár <pali@kernel.org> wrote:

> On Wednesday 06 April 2022 21:21:59 Marek Behún wrote:
> > On Wed, 6 Apr 2022 14:18:18 +0200
> > Pali Rohár <pali@kernel.org> wrote:
> >
> > > Armada 385 contains 64 lines of HD eFuse and 2 lines of LD eFuse. HD eFuse
> > > is used for secure boot and each line is 64 bits long + 1 lock bit. LD
> > > eFuse lines are 256 bits long + 1 lock bit. LD 0 line is reserved for
> > > Marvell Internal Use and LD 1 line is for General Purpose Data. U-Boot
> > > already contains HD eFuse reading and programming support.
> > >
> > > This patch implements LD eFuse reading support. LD 0 line is mapped to
> > > U-Boot fuse bank 64 and LD 1 line to fuse bank 65.
> > >
> > > LD 0 Marvell Internal Use line seems that was burned in factory with some
> > > data and can be read by U-Boot fuse command:
> > >
> > > => fuse read 64 0 9
> > >
> > > LD 1 General Purpose Data line is by default empty and can be read by
> > > U-Boot fuse command:
> > >
> > > => fuse read 65 0 9
> > >
> > > Signed-off-by: Pali Rohár <pali@kernel.org>
> >
> > I am not sure whether this can be used safely on Turris Omnia - there
> > was some issue with voltage or something, I know for sure that burning
> > does not work on Omnia, but I am not sure if the issue also prevents
> > stable reading.
>
> On A385 there is errata only for programming OTP bits.
>
> > Are the values you read always the same? Even across power cycles?
> >
> > Marek
>
> Reading is working fine and is stable also after power cycles. Marvell
> Internal Use contains data which are same after more reads.

In that case
Reviewed-by: Marek Behún <marek.behun@nic.cz>