Hi Tom, On 24 May 2017 at 06:56, Tom Rini <tr...@konsulko.com> wrote: > On Wed, May 24, 2017 at 10:18:12AM +0200, Heiko Stuebner wrote: >> Am Dienstag, 23. Mai 2017, 18:44:37 CEST schrieb Simon Glass: >> > Hi, >> > >> > On 23 May 2017 at 16:18, Andreas Färber <afaer...@suse.de> wrote: >> > > Hi Heiko, >> > > >> > > Am 23.05.2017 um 23:27 schrieb Heiko Stuebner: >> > >> Am Dienstag, 23. Mai 2017, 17:14:19 CEST schrieb Tom Rini: >> > >>> On Tue, May 23, 2017 at 11:03:23PM +0200, Mark Kettenis wrote: >> > >>>>> From: Heiko Stuebner <he...@sntech.de> >> > >>>>> Date: Tue, 23 May 2017 22:29:33 +0200 >> > >>>>> >> > >>>>> Hi Kever, Tom, >> > >>>>> >> > >>>>> Am Dienstag, 23. Mai 2017, 14:32:44 CEST schrieb Kever Yang: >> > >>>>>> This is not from kernel, seems the kernel mmc driver does not >> > >>>>>> support aliases now, >> > >>>>>> >> > >>>>>> thought I hope they both support the aliases for ordering. >> > >>>>> >> > >>>>> there was a lengthy discussion about the pros and cons of ordering >> > >>>>> mmc devices last year [0]. >> > >>>>> >> > >>>>> With the outcome that explicit ordering via aliases is not desired >> > >>>>> and the argument being that mmc devices are not so different from >> > >>>>> usb storage or scsi/sata devices whose ordering is random all the >> > >>>>> time. >> > >>>> >> > >>>> Aren't you intepreting the outcome of that discussion a bit too >> > >>>> broadly tough? That discussion seems to reject an explicit ordering >> > >>>> of mmc device names in the Linux kernel, mainly because better >> > >>>> mechanisms exist to refer to a particular device than its device >> > >>>> name/number. But that doesn't preclude having a meaningful set of >> > >>>> aliases for certain boards if there is some sort of canonical boot >> > >>>> order or if devices are actually numbered on a board? >> > >>>> >> > >>>> In OpenFirmware the primary purpose of these aliases is to specify >> > >>>> which device to boot from. >> > >> >> > >> readding the lkml-link for the above: >> > >> [0] https://lkml.org/lkml/2016/4/29/621 >> > >> >> > >> >> > >> As for that being to broad, wasn't that why Tom suggested moving that >> > >> to a -u-boot.dtsi file, because while generally not desired, it may >> > >> benefit uboot to get some sane boot order / type marks (emmc, sd-card), >> > >> but doesn't influence the core devicetree files that should ideally be >> > >> synced from the kernel or wherever? >> > > >> > > I think you're mixing three very distinct topics here: >> > > a) Whether Linux drivers should use aliases for ordering. >> > > b) Whether to add aliases in the DT. >> > > c) Sync'ing .dts files from Linux vs. local changes. >> > > >> > > I don't see what's wrong with b) as it is useful as a shorthand for >> > > access to a particular node, e.g. for U-Boot's fdt commands. >> > > >> > > Tom's point is that if a certain change is not in the Linux .dts and is >> > > needed for U-Boot, it should go into a U-Boot specific .dtsi file, so >> > > that the change doesn't get overwritten with the next .dts update from >> > > Linux. >> > > In the UEFI boot path we rely on a recent upstream-compatible DT being >> > > provided by U-Boot if none is installed by the OS in a way U-Boot can >> > > load, so the .dts will need to be re-sync'ed later on even if it doesn't >> > > affect U-Boot drivers. Therefore the commit messages also need to >> > > indicate where the .dts comes from, to avoid regressions on re-sync from >> > > different trees. >> > >> > Further to that, I think U-Boot needs the aliases because we refer to >> > devices by number. >> > >> > At a future date if U-Boot moves away from this to named devices, we >> > can revisit it. >> > >> > But so far as I can tell, without the aliases, U-Boot cannot operate >> > in a reliable, repeatable manner. >> >> ok, then never mind. You people probably know better what makes >> sense in an u-boot context :-) . > > Yeah, but it's one of those things I don't quite understand about why we > need to put non-project-specific (ie it's not a u-boot,xxx thing) into > our spot to append the dts. If we're talking about good, valid DT > content (ie nearly every SoC manual I've seen says MMC1 is ..., MMC2 is > ..., etc, so it's hardware description) why can't it be in the upstream > dts file and simply ignored by the kernel if it doesn't want it?
I agree that makes sense. I cannot think of a reason that the DT should be restricted to contain things only useful to Linux. Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
