On Fri, 2 Mar 2018 16:24:22 +0000 Andre Przywara <andre.przyw...@arm.com> wrote:
> Hi, > > On 02/03/18 15:58, Maxime Ripard wrote: > > On Fri, Mar 02, 2018 at 12:56:52AM +0000, Andre Przywara wrote: > >> Linux kernels before 4.12-rc1 don't know about the AXP803 PMIC, so can't > >> enable the MMC driver with the current DT anymore, because that now > >> depends on this regulator. > > > > Given that only I2C, USB and MMC were supported at the time, is it > > really worth it? There's a lot of incentive to move to a newer kernel > > given the minimal support it had at the time. > > Yeah, this is somewhat true, although serial, USB and MMC are somewhat > enough if one uses a USB Ethernet or WiFi adapter. And the kernel choice > might not always a decision of the user (thinking of distributions here). > But I was actually unsure about this as well, and wanted to hear some > opinions. > > One thing that comes to mind is other OSes. Does anyone know how if for > instance FreeBSD supports the AXP and its Linux bindings? The whole goal > of this series is to allow booting OSes with U-Boot's DT copy > ($fdtcontroladdr), so if this patch would make their life easier, it > might be worth it. Not yet but I started the work a few days ago and we should have a driver soon. > Regarding the whole forward/backward compatibility: > I clearly see the difficulty in coming up with a "perfect" DT from day > one, especially for badly documented SoCs, where mainlining is driven by > hobbyists. So I was wondering if we introduce a grace period, where we > declare the DT "unstable" or "subject to incompatible changes" for some > releases (not too many). In hindsight we might declare 4.12 the stable > DT base for the A64, for instance. > This would allow us to start upstreaming early, with a small feature set > only (just serial + clocks + pinctrl, as for the H6). Additional > features (PMIC) might then add small incompatibilities (like this one > here), until we are reasonably confident about the DT. > Does that sound useful? > > So I am not insisting on this patch, but wanted to point out the > problems that those seemingly innocent DT changes create and would be > happy if we can at least try to avoid them in the future. > > Cheers, > Andre. > _______________________________________________ > U-Boot mailing list > U-Boot@lists.denx.de > https://lists.denx.de/listinfo/u-boot -- Emmanuel Vadot <m...@bidouilliste.com> <m...@freebsd.org> _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot