From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dirk Behme Subject: Re: Clocks used by another OS/CPU Date: Thu, 29 Jun 2017 14:55:14 +0200 Message-ID: References: <50911172-8fa1-8341-0ed0-d40f00d9392c@de.bosch.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-renesas-soc-owner@vger.kernel.org To: Geert Uytterhoeven Cc: Michael Turquette , Stephen Boyd , Rob Herring , Mark Rutland , Ulf Hansson , "Rafael J. Wysocki" , Kevin Hilman , Linux-Renesas , linux-clk , "linux-arm-kernel@lists.infradead.org" , "devicetree@vger.kernel.org" , Linux PM list List-Id: linux-pm@vger.kernel.org On 29.06.2017 14:45, Geert Uytterhoeven wrote: > Hi Dirk, > > On Thu, Jun 29, 2017 at 2:07 PM, Dirk Behme wrote: >> On 29.06.2017 13:56, Geert Uytterhoeven wrote: >>> On Thu, Jun 29, 2017 at 11:27 AM, Geert Uytterhoeven >>> 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. Well, it seems to be the best solution recent mainline gives us and seems to work ;) And for me it looks at least better than the other solution I've seen so far: Remove the 'cr7', 'canfd' etc lines completely from the kernel. Best regards Dirk