From mboxrd@z Thu Jan 1 00:00:00 1970 From: Albert ARIBAUD Date: Wed, 8 Jul 2015 16:04:48 +0200 Subject: [U-Boot] [PATCH 1/3] dm: dts: ls2085a: Bring in ls2085a dts files from linux kernel In-Reply-To: References: <1435319316-28702-1-git-send-email-haikun.wang@freescale.com> <20150708111933.4da01836@lilith> Message-ID: <20150708160448.5537a82a@lilith> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hello Sharma, On Wed, 8 Jul 2015 10:31:45 +0000, Sharma Bhupesh wrote: > Hi Albert > > > -----Original Message----- > > From: Albert ARIBAUD [mailto:albert.u.boot at aribaud.net] > > Sent: Wednesday, July 08, 2015 2:50 PM > > To: Sharma Bhupesh-B45370 > > Cc: Wang Haikun-B53464; Bin Meng; Russell King; Mark Rutland; Sun York- > > R58495; Kushwaha Prabhakar-B32579; u-boot at lists.denx.de > > Subject: Re: [U-Boot] [PATCH 1/3] dm: dts: ls2085a: Bring in ls2085a dts > > files from linux kernel > > > > Hello Sharma, > > > > On Wed, 8 Jul 2015 07:31:47 +0000, Sharma Bhupesh > > wrote: > > > > -----Original Message----- > > > > From: U-Boot [mailto:u-boot-bounces at lists.denx.de] On Behalf Of Wang > > > > Haikun On 7/8/2015 3:13 PM, Bin Meng wrote: > > > > > Hi, > > > > > > > > > > On Wed, Jul 8, 2015 at 2:51 PM, Wang Haikun > > > > > > > > > wrote: > > > > >> On 6/26/2015 7:53 PM, Haikun Wang wrote: > > > > >>> From: Haikun Wang > > > > >>> > > > > >>> Bring in required device tree files for ls2085a from Linux. > > > > >>> These are initially unchanged and have a number of pieces not > > > > >>> needed > > > > by U-Boot. > > > > >> Hi Simon, > > > > >> > > > > >> I got below comment when review this patch internal. > > > > >> Please help me confirm. > > > > >> > > > > >> "For new platforms like ARM64, it was discussed to not duplicate > > > > >> the DTS in u-boot and Linux, simply because that will break > > > > >> compatibility with other bootloaders like Linaro's BootMonitor > > > > >> and UEFI bootloader, which do not place the DTS in the > > > > >> bootloader. Also in near future, with DTS being replaced by ACPI > > > > >> gradually for ARM64 platforms, it was discussed that in a longer > > > > >> run it would be beneficial to move DTS out of both u-boot and > > Linux and maintain it as a separate tree." > > > > >> > > > > > > > > > > I think UEFI + ACPI is only required for ARMv8 servers, not for > > > > > all > > > > > ARMv8 processors. Is ls2085a a processor targeting the server > > market? > > > > No, at least it's not our major market. > > > > I want to know whether we have made a conclusion that u-boot will > > > > not add > > > > Arm64 dts files? > > > > > > Adding Russell and Mark for their thoughts. > > > > > > AFAIK there were discussions to generate common DTS files for PPC and > > > ARM platforms, where it was discussed that in a longer run it would be > > > beneficial to move DTS out of both u-boot and Linux and maintain it as > > a separate tree. > > > > This might be what happens in the long term (and I pretty much agree with > > having DTS common to, and separate from, any project that uses them even > > though that means yet one more configuration item to manage at the full > > project delivery level), but precisely because it is a long term goal, it > > is not what's going on right now. > > > > In the interim, and AFAIAC, I'm fine with DTS files living in U-Boot. > > And I'd be finer yet with a simple way to specify where the DTS files can > > be searched for at build time, using e.g. an env var, something > > like: > > > > DTC_PATH = "/home/dev/linux/arch/arm/boot/dtc" tools/buildman/... > > > > I believe this would be quite easy to implement in both U-Boot and Linux > > with dtc_cpp_flags, by passing DTC_PATH as a -I option. > > > > One could even specify a set of paths, which would produce several -I > > options, for instance making dtc search first in U-Boot's own repo, then > > in the standalone DTS files projects repo (once a standalone DTS files > > project exists, that is). Looking in U-Boot first would allow using U- > > boot as a staging area for new DTS files until the standalone DTS project > > picks them up. > > > > I am in agreement, with what you said above, but we must be careful to not introduce > any dependencies in Linux dts assuming that the u-boot dts will fix them up or implement > them. With Linaro BootMonitor and UEFI like bootloaders, which don't have the comprehensive > DTS infrastructure, nor the dts fixup infrastructure, we should be pushing u-boot > dts changes back to the Linux dts, to make sure that Linux boots fine with other > ARM64 bootloaders like UEFI. Agreed: DTS files should be designed to work with all projects that use them, even DTS files temporarily provided within U-Boot. > Regards, > Bhupesh Amicalement, -- Albert.