Dear Daniel, On Fri, 30 Oct 2015 13:37:01 +0100 Daniel Lezcano wrote:
> 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 <jszh...@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 Yes, I don't need the dw apb timer if we have arch timer, > 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 ? Yes, if we have arch timer, I prefer to use it for clockevent and delay. Could you please provide suggestion how to handle this case? Thanks, Jisheng -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
