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Date:   Thu, 1 Apr 2021 13:58:05 +0300
From:   Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
To:     Andreas =?iso-8859-1?Q?F=E4rber?= <afaerber@suse.de>,
        Manivannan Sadhasivam <mani@kernel.org>
Cc:     Rob Herring <robh+dt@kernel.org>, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-actions@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/6] Add support for Actions Semi Owl socinfo
Message-ID: <20210401105805.GA1998829@BV030612LT>
References: <cover.1617110420.git.cristian.ciocaltea@gmail.com>
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 <20210401094041.GA1993499@BV030612LT>
 <20210401102717.GF14052@work>
 <252dd954-c8f1-fa2a-c37a-ede386fc9d43@suse.de>
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Hi Mani, Andreas,

On Thu, Apr 01, 2021 at 12:49:37PM +0200, Andreas F?rber wrote:
> Hi,
> 
> On 01.04.21 12:27, Manivannan Sadhasivam wrote:
> > On Thu, Apr 01, 2021 at 12:40:41PM +0300, Cristian Ciocaltea wrote:
> >> On Thu, Apr 01, 2021 at 10:54:38AM +0530, Manivannan Sadhasivam wrote:
> >>> On Tue, Mar 30, 2021 at 04:48:15PM +0300, Cristian Ciocaltea wrote:
> >>>> This patchset adds a socinfo driver which provides information about
> >>>> Actions Semi Owl SoCs to user space via sysfs: machine, family, soc_id,
> >>>> serial_number.
> >>>>
> >>>> Please note the serial number is currently available only for the S500
> >>>> SoC variant.
> >>>>
> >>>> This has been tested on the S500 SoC based RoseapplePi SBC.
> >>>>
> >>>
> >>> Is this the soc_id provided by the vendor bootloader (uboot)? If so, under
> >>> what basis it provides? I don't think the SoC has the provision for
> >>> soc_id based on HW parameters.
> >>
> >> No, the soc_id is not provided by the bootloader, or at least I couldn't
> >> identify any related implementation. Instead, I provided this via the
> >> driver itself, since I've encountered this approach in some other soc
> >> drivers as well (e.g. imx/soc-imx.c, versatile/soc-integrator.c). 
> >>
> > 
> > Sorry, I was referring to serial_number. Since your comment says so, can
> > you point to the corresponding code?
> 
> Seconded that this needs to be better understood. If this is just a
> convention of some downstream U-Boot that's not implemented in mainline
> (and maybe not even for Guitar or Labrador? tested on RoseapplePi only),
> it might not be worth its own reserved-memory based kernel driver?

The serial number is actually provided by the s500-bootloader for which
Actions did not provide the source code, at least it is not available
in the xapp github repo. I did not find anything related to this in
downstream U-Boot.

Kind regards,
Cristi

> Implementing a standard interface such as DMI tables or a DT property in
> mainline U-Boot may be more useful then. Is it still Mani's S900 only?
> 
> Regards,
> Andreas
> 
> -- 
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