Hi Dirk,
On Thu, Jun 29, 2017 at 2:07 PM, Dirk Behme <dirk.behme@xxxxxxxxxxxx> wrote:
> On 29.06.2017 13:56, Geert Uytterhoeven wrote:
>> On Thu, Jun 29, 2017 at 11:27 AM, Geert Uytterhoeven
>> <geert@xxxxxxxxxxxxxx> wrote:
>>> CC clock, ARM, DT, PM people
>>>
>>> TL;DR: Clocks may be in use by another CPU not running Linux, while Linux
>>> disables them as being unused.
>>
>>> Of course this is not limited to clocks, but also to e.g. PM domains.
>>
>> BTW, how do you prevent Linux from powering down the CR7 PM domain,
>> which contains the Cortex R7?
>
> The idea is
>
> --- a/drivers/soc/renesas/r8a7795-sysc.c
> +++ b/drivers/soc/renesas/r8a7795-sysc.c
> @@ -38,7 +38,8 @@ static const struct rcar_sysc_area r8a7795_areas[]
> __initconst = {
> { "ca53-cpu3", 0x200, 3, R8A7795_PD_CA53_CPU3, R8A7795_PD_CA53_SCU,
> PD_CPU_NOCR },
> { "a3vp", 0x340, 0, R8A7795_PD_A3VP, R8A7795_PD_ALWAYS_ON
> },
> - { "cr7", 0x240, 0, R8A7795_PD_CR7, R8A7795_PD_ALWAYS_ON
> },
> + { "cr7", 0x240, 0, R8A7795_PD_CR7,
> R8A7795_PD_ALWAYS_ON,
> + PD_CPU_NOCR },
> { "a3vc", 0x380, 0, R8A7795_PD_A3VC, R8A7795_PD_ALWAYS_ON
> },
> { "a2vc0", 0x3c0, 0, R8A7795_PD_A2VC0, R8A7795_PD_A3VC },
> { "a2vc1", 0x3c0, 1, R8A7795_PD_A2VC1, R8A7795_PD_A3VC },
>
>
> Not finally tested, though.
Pretending the CR7 PM Domain can only be controlled through WFI/APMU only should
work.
But IMHO it is a hack, just like your solution for the CANFD clock.
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
