Messages in this thread | | | Subject | Re: [PATCH] clocksource: dw_apb_timer_of: support timer-based delay | From | Daniel Lezcano <> | Date | Fri, 30 Oct 2015 13:37:01 +0100 |
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On 10/30/2015 12:09 PM, Jisheng Zhang wrote: > Dear Daniel, > > On Fri, 30 Oct 2015 11:44:46 +0100 > Daniel Lezcano <daniel.lezcano@....> wrote: > >> On 10/30/2015 09:27 AM, Jisheng Zhang wrote: >>> Implement an ARM delay timer to be used for udelay(). This allows us to >>> skip the delay loop calibration at boot on Marvell BG2, BG2Q, BG2CD >>> platforms. And after this patch, udelay() will be unaffected by CPU >>> frequency changes. >>> >>> Signed-off-by: Jisheng Zhang <jszhang@marvell.com> >>> --- >>> drivers/clocksource/Kconfig | 10 ++++++++++ >>> drivers/clocksource/dw_apb_timer_of.c | 16 ++++++++++++++++ >>> 2 files changed, 26 insertions(+) >>> >>> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig >>> index a7726db..7b081805 100644 >>> --- a/drivers/clocksource/Kconfig >>> +++ b/drivers/clocksource/Kconfig >>> @@ -29,6 +29,16 @@ config DW_APB_TIMER_OF >>> select DW_APB_TIMER >>> select CLKSRC_OF >>> >>> +config DW_APB_TIMER_BASED_DELAY >>> + bool "DW APB timer based delay" >>> + depends on ARM && DW_APB_TIMER_OF >>> + default n >>> + help >>> + This option enables support for using the DW APB timer to >>> + implement timer-based delay. It is useful for skiping the >>> + delay loop calibration at boot on some platforms. And the >>> + udelay() will be unaffected by CPU frequency changes. >>> + >> >> Why do you want it to be optional ? >> > > Because in some platforms which has arm arch timer, this dw apb timer > delay isn't needed, the arch timer is better. So we want it be optional > so that the platforms which need this feature select it manually when config > the kernel.
Correct me if I am wrong. If you have the arch timer, you don't need the dw apb timer at all, no ? So the selection would be arch arm timer *or* dw_apb_timer ? not arch_arm_timer for delay and dw_apb_timer for clockevents, right ?
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