From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kumar Gala Subject: Re: [PATCH v2 1/3] devicetree: bindings: Document qcom,msm-id and qcom,board-id Date: Tue, 10 Mar 2015 14:57:47 -0500 Message-ID: <7DA73171-01A5-4158-9A69-015B62D2D7E8@codeaurora.org> References: <1425503602-24916-1-git-send-email-galak@codeaurora.org> <3A588B25-66ED-4BB5-8C8F-D050D8A2F9F3@codeaurora.org> <10886228.vUHyKm1ubP@wuerfel> Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <10886228.vUHyKm1ubP@wuerfel> Sender: linux-arm-msm-owner@vger.kernel.org To: Arnd Bergmann Cc: Olof Johansson , Kevin Hilman , linux-arm-msm , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "arm@kernel.org" , "devicetree@vger.kernel.org" , =?windows-1252?Q?Heiko_St=FCbner?= List-Id: devicetree@vger.kernel.org On Mar 10, 2015, at 2:52 PM, Arnd Bergmann wrote: > On Tuesday 10 March 2015 13:10:08 Kumar Gala wrote: >>>>>>>>>>> The top level qcom,msm-id and qcom,board-id are utilized by= bootloaders >>>>>>>>>>>> on Qualcomm MSM platforms to determine which device tree s= hould be >>>>>>>>>>>> utilized and passed to the kernel. >>>>>>>>>>>>=20 >>>>>>>>>>>> Cc: >>>>>>>>>>>> Signed-off-by: Kumar Gala >>>>>>>>>>>=20 >>>>>>>>>>> Is this the special magic that allows qcom bootloaders to t= ake a kernel >>>>>>>>>>> plus multiple DTBs and figure out which DTB to pass? >>>>>>>>>>>=20 >>>>>>>>>>> Kevin >>>>>>>>>>=20 >>>>>>>>>> yes >>>>>>>>>=20 >>>>>>>>> That's a bummer. >>>>>>>>>=20 >>>>>>>>> Luckily, the solution for upstream is still quite simple: Pro= vide only >>>>>>>>> one devicetree, and it'll be used, right? >>>>>>>>=20 >>>>>>>> We can provide only one, we still need the IDs in the DT. >>>>>>>=20 >>>>>>> How are the DTS provided? Concatenated with the kernel, or in a >>>>>>> wrapped data format? Or in a separate partition from the kernel= ? >>>>>>=20 >>>>>> Its a wrapped data format that is than concatenated with the ker= nel if I remember correctly. >>>>>=20 >>>>> Then you should be able to create a tool that can write this conc= atenated >>>>> format and insert these properties from a table that matches the = boot >>>>> loader, right? >>>>>=20 >>>>> Arnd >>>>=20 >>>> Are you suggesting the tool insert the properties in the DT? I=92= m not sure I understand what the point of doing that would be. >>>=20 >>> To insert platform-local properties that mean nothing outside of th= e >>> firmware packaging of the device trees, which is the case here? >>>=20 >>> I think the idea of having the installer script inserting them is >>> quite reasonable in this case. >>>=20 >>>=20 >>> -Olof >>=20 >> These values are static, so not sure what the point of having the in= staller script do that? >>=20 >=20 > It combines two hacks to work around a nonstandard boot loader. > Once the bootloader is fixed, you can stop using that script. >=20 > Arnd I feel as if I=92m missing something here. If we just have the propert= ies in the .dts files I don=92t need to change anything ever, no script= , no worries about working with old or new boot loaders, etc. - 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