Hi Dirk, On Thu, Jun 29, 2017 at 3:18 PM, Dirk Behme <dirk.behme@xxxxxxxxxxxx> wrote: > On 29.06.2017 13:18, Geert Uytterhoeven wrote: >> On Thu, Jun 29, 2017 at 12:28 PM, Dirk Behme <dirk.behme@xxxxxxxxxxxx> >> wrote: >>> On 29.06.2017 11:27, Geert Uytterhoeven wrote: >>>> TL;DR: Clocks may be in use by another CPU not running Linux, while >>>> Linux >>>> disables them as being unused. >>>> On r8a7795, there are several Cortex A cores running Linux, and a Cortex >>>> R7 >>>> core which may run another OS. >>>> This is an interesting issue, and relevant to other SoCs, too. > First of all, just the clocks we know (*) are used by the R7 side *and* are > disabled by the kernel (for a practical demo this are e.g. ~7 clocks). > > (*) Yes, this is board (and R7 software) related. And yes, this might result > in board specific r8a7795_crit_mod_clks/r8a7795_crit_core_clks[] tables. So > yes, most probably device tree would be an option. While there is > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/clk/clk.c#n3402 > > unfortunately > > a) its marked as "Do not use this function" > > and > > b) even if we would ignore (a) we couldn't figure how to use this for the > RCar3 clocks (being no clock expert) You cannot, as it only supports the legacy one-clock-per-node style. You can use it on e.g. sd2_clk in arch/arm/boot/dts/r8a7791.dtsi, until R-Car Gen2 is switched to the new CPG/MSSR driver. 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
