From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Subject: Re: [RFC:PATCH dtc-1.3.0] dtc: Add --strip-disabled option to dtc. Date: Tue, 21 Aug 2012 10:11:59 +1000 Message-ID: <20120821001159.GJ29724@truffula.fritz.box> References: <1345034325-26656-1-git-send-email-srinivas.kandagatla@st.com> <20120817060415.GC29724@truffula.fritz.box> <502E3632.70208@freescale.com> <502E52F3.7090404@st.com> <502E64F9.2020400@freescale.com> <5031F706.3050509@st.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <5031F706.3050509-qxv4g6HH51o@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Srinivas KANDAGATLA Cc: "mmarek-AlSwsSmVLrQ@public.gmane.org" , Scott Wood , "devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , Timur Tabi List-Id: devicetree@vger.kernel.org On Mon, Aug 20, 2012 at 09:36:22AM +0100, Srinivas KANDAGATLA wrote: > On 17/08/12 16:36, Timur Tabi wrote: > > Srinivas KANDAGATLA wrote: > >> If you know in advance that device on that SOC is broken, then I guess > >> "Fail"/"Failed" can be used in status property. > >> > >> One user of this flag in kernel device trees is > >> ./arch/powerpc/boot/dts/mpc8313erdb.dts > > /* Remove this (or change to "okay") if you have > > * a REVA3 or later board, if you apply one of the > > * workarounds listed in section 8.5 of the board > > * manual, or if you are adapting this device tree > > * to a different board. > > */ > > status = "fail"; > > > > I'm not sure this is the right way to do it. > I agree, the way fail status is used is pretty much redundant to what > "disabled" is used for. > I think the device trees files should have status as "okay" or "ok" or > "disabled" or skip status property totally. > > > Normally, the boot loader > > should be able to detect the board revision, and it should dynamically set > > the 'status'. We have other devices that fail if a work-around is not > > applied, and we don't use this approach. > > > > But assuming that this really is the best approach, then it would make > > sense for --strip-disabled to leave this node in the dtb, because > > otherwise there would be no way to re-enable it. > --strip-disabled should still get rid for nodes marked as failed > as-well, because fail means something serious and un-recoverable. > > I think bootloader should not even consider nodes with status as > fail, as the device is unlikely to become operational without > repair. I do worry about the usability implications of that - if a device that was previously working stops working and is marked as "failed" it's fairly easy for the user/admin to see what's going on. If the device simply vanishes completely that would be rather more mysterious. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson