Hi Arnd, On Tue, May 23, 2017 at 4:17 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Tue, May 23, 2017 at 11:49 AM, Geert Uytterhoeven > <geert@xxxxxxxxxxxxxx> wrote: >> On Mon, May 22, 2017 at 5:11 PM, Olof Johansson <olof@xxxxxxxxx> wrote: >>> On Mon, May 22, 2017 at 4:44 AM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: >>>> On Fri, May 19, 2017 at 9:34 PM, Olof Johansson <olof@xxxxxxxxx> wrote: >>> >>> Yeah, asking people to spread out across releases would remove >>> dependencies a lot, but it would also slow down progress and frustrate >>> a lot of contributors so we don't do that. >> >> The above works fine for new support, or for new platforms. >> >> There's still support being migrated from platform code to DT, which >> requires three steps: >> 1. New DT-aware driver support, >> 2. DT update to use the new driver support, >> 3. Clean up platform code after optional DTB backwards compatibility >> grace period, >> To make matters worse, 1 may conflict with the existing platform code, >> and 2 must sometimes not be done before 1. Hence you may need three kernel >> releases. >> So we're already planning now what to clean up for v4.15 ;-) >> >> Would it be acceptable to do step 2 in the same release, after the driver >> support has entered in -rc1? I know this is more than just replacing >> numbers by symbolic values. > > I'd say it really depends on the individual case. Do you have a particular > platform in mind? E.g. For some of the more obsolete platforms that > Linus Walleij has worked on over time, we have sometimes relaxed the > rules about clean bisection and just merged everything in parallel, knowing > that nobody else was likely to run that code on a vanilla kernel anyway. This is for Renesas R-Car Gen2 SoCs, so we do care about DT backward compatibility (for a while), and about bisection. Last headache was "[PATCH v4 00/23] soc: renesas: Add R-Car RST driver for obtaining mode pin state" (https://lkml.org/lkml/2016/10/21/500). This used a shared immutable branch, but that caused several merge conflicts. Next one will be smaller, as it's not really moving functionality from platform code to DT, but switching to a new and better clock driver framework, so there's only the dependency of DT on the new driver "[PATCH v2 00/10] clk: renesas: rcar-gen2: Add new CPG/MSSR drivers" (https://lkml.org/lkml/2017/5/19/212) I'll go create an inventory of stuff in platform code for Renesas SoCs that still needs to be converted to DT... Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
