Re: [PATCH v2] ARM: dts: sunxi: Add sid for a83t

From: Kyle Evans
Date: Thu Dec 21 2017 - 10:31:30 EST

On Thu, Dec 21, 2017 at 9:26 AM, Maxime Ripard
<maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote:
> Hi,
> On Thu, Dec 21, 2017 at 09:19:24AM -0600, Kyle Evans wrote:
>> On Thu, Dec 21, 2017 at 8:55 AM, Maxime Ripard
>> <maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote:
>> > Hi Kyle,
>> >
>> > On Tue, Dec 19, 2017 at 03:05:23PM -0600, kevans91@xxxxxxx wrote:
>> >> Allwinner a83t has a 1 KB sid block with efuse for security rootkey and
>> >> thermal calibration data, add node to describe it.
>> >>
>> >> a83t-sid is not currently supported by nvmem/sunxi-sid, but it is
>> >> supported in an external driver for FreeBSD.
>> >>
>> >> Signed-off-by: Kyle Evans <kevans91@xxxxxxx>
>> >
>> > The patch looks fine in itself, but we've had a number of issues with
>> > the register layout (and access patterns) in the past, so I'd rather
>> > have something that works in Linux too if possible.
>> I have a patch that I think should make it work fine on Linux [1], but
>> I'm afraid I have little to no capability to test it myself and so I
>> did not add it as well.
>> I do know that the rootkey is offset 0x200 into the given space [2],
>> as is the case with the H3, and that the readout quirk is not needed.
>> I wasn't 100% sure that the a83t has 2Kbit worth of efuse space as the
>> H3, but I do know that thermal data can be found at 0x34 and 0x38 in
>> this space.
> Then maybe we should leave it aside until someone takes some time on
> the A83t. The good news is that the binding itself looks fine, so as
> far as FreeBSD goes, there shouldn't be anything preventing you from
> using it I guess.

Yeah, we've had this exact binding in our own copy of DTS up until a
recent point when we flipped the switch to pulling DT from Mainline
Linux and trying to upstream changes instead of having a bunch of
local modifications in our tree.

> Chen-Yu, what do you think?
> Thanks!
> Maxime
> --
> Maxime Ripard, Free Electrons
> Embedded Linux and Kernel engineering