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

From: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
To: Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org>
Cc: Emmanuel Vadot <manu-xXdDKFdH5B3kFDPD4ZthVA@public.gmane.org>,
	Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>,
	devicetree <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	linux-kernel
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Russell King <linux-I+IVW8TIWO2tmTQ+vhA3Yw@public.gmane.org>,
	linux-sunxi <linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>,
	Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Srinivas Kandagatla
	<srinivas.kandagatla-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	Kyle Evans <kevans91-OYTqUY/oFF8@public.gmane.org>,
	linux-arm-kernel
	<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>
Subject: Re: [PATCH v2] ARM: dts: sunxi: Add sid for a83t
Date: Thu, 4 Jan 2018 15:01:19 +0100	[thread overview]
Message-ID: <20180104140119.5pyfihp4zs2poz35@flea.lan> (raw)
In-Reply-To: <CAGb2v64mf-ihyOs-WJZuVa4Yib3Szp90RZu_a1EeQ1LJXnoXEQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

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On Fri, Dec 22, 2017 at 06:11:52PM +0800, Chen-Yu Tsai wrote:
> On Fri, Dec 22, 2017 at 6:07 PM, Emmanuel Vadot <manu-xXdDKFdH5B3kFDPD4ZthVA@public.gmane.org> wrote:
> > On Fri, 22 Dec 2017 09:35:08 +0100
> > Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> wrote:
> >
> >> On Thu, Dec 21, 2017 at 07:09:03PM +0100, Emmanuel Vadot wrote:
> >> >
> >> >  Hi Maxime,
> >> >
> >> > On Thu, 21 Dec 2017 16:26:30 +0100
> >> > Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> 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-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> wrote:
> >> > > > > Hi Kyle,
> >> > > > >
> >> > > > > On Tue, Dec 19, 2017 at 03:05:23PM -0600, kevans91-OYTqUY/oFF8@public.gmane.org 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-OYTqUY/oFF8@public.gmane.org>
> >> > > > >
> >> > > > > 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.
> >> >
> >> >  Take some time on the Linux driver and do not apply this patch for
> >> > now you mean ?
> >>
> >> Yep.
> >>
> >> Maxime
> >
> >  Since linux doesn't have the compatible in it's driver what would
> > be the harm to add the node in the DTS ? If a quirks is needed because
> > some region is weird this would go in the driver right ? I don't see a
> > technical problem for adding this node right now.
> >  If Kyle confirm the lenght of the region and that no quirk is needed
> > will it be enough ?
> 
> I guess I wasn't very clear. I'm OK with the patch going in. The device
> node currently says nothing about how much efuse space there is. The
> memory region covers that and the control section, and the size matches
> what the memory map says.
> 
> The size and offset of the efuse space would be dealt with in the driver.

Let's merge it then.

Acked-by: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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