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Date:   Thu, 1 Apr 2021 16:37:52 +0530
From:   Manivannan Sadhasivam <mani@kernel.org>
To:     Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
Cc:     Andreas =?iso-8859-1?Q?F=E4rber?= <afaerber@suse.de>,
        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,
        matheus@castello.eng.br
Subject: Re: [PATCH v2 0/6] Add support for Actions Semi Owl socinfo
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+ Matheus

On Thu, Apr 01, 2021 at 01:58:05PM +0300, Cristian Ciocaltea wrote:
> 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.
> 

Hmm, then we can consider this as the firmware dependent property. But
can we get consensus that this is common for all S500 SoCs? Maybe,
Matheus can verify it on Labrador?

I don't think adding a SOCINFO driver for a single board is a good idea.

Thanks,
Mani

> 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
> > 
> > -- 
> > SUSE Software Solutions Germany GmbH
> > Maxfeldstr. 5, 90409 N?rnberg, Germany
> > GF: Felix Imend?rffer
> > HRB 36809 (AG N?rnberg)