From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kumar Gala Subject: Re: [PATCH 1/2] Documentation: devicetree: root node serial-number property documentation Date: Thu, 16 Apr 2015 10:53:43 -0500 Message-ID: References: <1427564371-26039-1-git-send-email-contact@paulk.fr> <1429175421.2483.1.camel@collins> <1429199145.2563.9.camel@collins> Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2098\)) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1429199145.2563.9.camel@collins> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Paul Kocialkowski Cc: Mark Rutland , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Russell King , Pawel Moll , Ian Campbell , Stefan Agner , Hans De Goede , Rob Herring , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org > On Apr 16, 2015, at 10:45 AM, Paul Kocialkowski wr= ote: >=20 > Le jeudi 16 avril 2015 =C3=A0 10:23 -0500, Kumar Gala a =C3=A9crit : >>> On Apr 16, 2015, at 9:36 AM, Rob Herring wr= ote: >>>=20 >>> On Thu, Apr 16, 2015 at 4:10 AM, Paul Kocialkowski wrote: >>>> Le jeudi 16 avril 2015 =C3=A0 09:56 +0200, Stefan Agner a =C3=A9cr= it : >>>>> On 2015-03-28 18:39, Paul Kocialkowski wrote: >>>>>> Signed-off-by: Paul Kocialkowski >>>>>=20 >>>>> I think this is a worthwhile standardization. >>>>>=20 >>>>> Acked-by: Stefan Agner >>>>=20 >>>> Thanks! I should also add a commit message in v2 mentioning that t= his is >>>> already used in open firmware and reported by lshw. >>>=20 >>> With that, >>>=20 >>> Acked-by: Rob Herring >=20 > [snip] >=20 >> I feel like this is a little lite either in the doc or commit messag= e. >> Is the string completely arbitrary? Is it meant to match labeling o= n >> a board or case? Is this meant to be used by the kernel at all? >=20 > I guess it doesn't really matter what it is, as long as it's a string= =2E > The kernel does not suggest any use for it either, it's just made > available to userspace through cpuinfo. >=20 > Now if there is a particular use for this in user-space, it would hav= e > to match some standards. For instance, it Android, ro.serialno is > usually a 16-bytes (plus one null byte) representation of a 64 bit > number. For USB, I recall it is usually a 32 bytes string (including = the > null byte), but may be extended to more. >=20 > What the string actually represents depends and some SOCs have serial > number bytes (I know that omap and sunxi have some for instance, that > are usually used) while other devices may take it from somewhere else= =2E > In any case, it doesn't really matter and is not up to the kernel any= way > since it is just passed through from the bootloader. >=20 > Thus, I don't think it's very relevant to mention it in either the > documentation or the commit message. So you say =E2=80=98board=E2=80=99 in the patch, since it could be SoC = specific, we should probably clean up the wording a bit. I=E2=80=99m j= ust saying when someone reads this 6 months or a year later and tries t= o figure out what the purpose of the property is they don=E2=80=99t rea= lly have enough info. Putting some examples in the commit message of w= hat possibly usages is I think a reasonable thing. - k --=20 Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora For= um, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html