From mboxrd@z Thu Jan 1 00:00:00 1970 From: grygorii.strashko@ti.com (Grygorii Strashko) Date: Fri, 2 Dec 2016 12:02:23 -0600 Subject: [PATCH 2/2] ARM: omap: timers: reduce rating of gp_timer clocksource In-Reply-To: <20161202164714.GB4705@atomide.com> References: <1479968355-18860-1-git-send-email-j-keerthy@ti.com> <1479968355-18860-2-git-send-email-j-keerthy@ti.com> <20161202164714.GB4705@atomide.com> Message-ID: <14878d85-1b08-5df1-4e67-6f982ba72019@ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 12/02/2016 10:47 AM, Tony Lindgren wrote: > * Grygorii Strashko [161129 08:43]: >> >> >> On 11/24/2016 12:19 AM, Keerthy wrote: >>> From: Grygorii Strashko >>> >>> Now ARM Global timer (rating 300) will not be selected as clocksource, >>> because it's initialized after OMAP GP Timer (rating 300) and >>> Timekeeping core will not allow to replace clocksource with new one if >>> both of them have the same rating. >>> >>> Reduce rating of OMAP GP Timer (300->290) when it's used as >>> clocksource device - this will allow to select ARM Global timer (300) >>> as clocksource when enabled. >>> >>> Signed-off-by: Grygorii Strashko >>> Signed-off-by: Dave Gerlach >>> Signed-off-by: Keerthy >> >> Unfortunately, this patch has dependency [1] and can't be used alone as >> it will cause ARM Global timer to be selected as clocksource >> always on am437x and this will kill cpuidle, because ARM Global timer >> is not in always_on domain. >> >> The intention of enabling ARM Global timer is only for non-pm aware use >> cases for RT-kernel latency improvement - where deep cpuidle states are not >> enabled. > > Yeah we need to fix up things to be able to change the clocksource > in addition to clockevent. However, currently only cpuidle_coupled > knows when the whole system is idle, so quite a bit of work is > needed to do that in a sane way. Also sched_clock and timer_delay ;) > > What about the first patch in this series? > Fist one is ok. It was originally posted long time ago. -- regards, -grygorii