[PATCH] clocksource: dw_apb_timer_of: support timer-based delay

Dear Arnd

On Tue, 3 Nov 2015 09:49:32 +0100
Arnd Bergmann wrote:

On Tuesday 03 November 2015 14:59:40 Jisheng Zhang wrote:

quoted

quoted

On Monday 02 November 2015 11:03:34 Jisheng Zhang wrote:  

quoted

On Fri, 30 Oct 2015 13:42:01 +0100 Arnd Bergmann wrote:    

I'd be happier with a solution that keeps the DT describing the hardware
and not the way we expect Linux to use it, and instead has some heuristic
in the selection of the delay timer. At the moment, we purely base this
on the frequency, which as you say is suboptimal.

One possible way to improve this would be to add an optional 'latency'
property to the DT nodes (or the driver), and use a combination of latency
and resolution to make the decision.  

Got it. Thanks for the suggestions. The 'latency' here seems a 'rating'
similar as the one in clocksource. I will cook a series for review:

patch 1 to make register_current_timer_delay() aware of 'rating'

patch 2 to set rating of arch timer as 400

patch 3 to add timer based delay support to dw_apb_timer whose rating is 300  

Ok. Just to make sure I got this right: your plan is to use the existing
'rating' setting as a primary indication, and fall back to comparing the
frequency if the rating is the same?

Yes, this is my plan.

Thanks,
Jisheng