On 22.12.2013 02:29, Ian Campbell wrote: > On Sun, 2013-12-22 at 01:21 +0000, Ian Campbell wrote: >> On Sat, 2013-12-21 at 23:23 +0100, Vladimir 'φ-coder/phcoder' Serbinenko >> wrote: >>> On 15.12.2013 16:23, Ian Campbell wrote: >>>> From: Ian Campbell <ian.campb...@citrix.com> >>>> >>>> u-boot's API_GET_TIMER returns the current time in ms by directly exposing >>>> the >>>> internal get_timer which is in ms, which isn't all that clearly documented >>>> but >>>> is obvious from the use within u-boot and is mentioned in >>>> http://www.denx.de/wiki/U-Boot/TaskTimerAPI. >>>> >>> During tests on my raspberry pi, I actually experienced the exact >>> opposite. On PI timer API is in microseconds. >>> Are you sure you made no mistake? >> >> I'm quite sure that on the Midway platform get_timer was returning ms >> and the 5s grub countdown took 5s after my fix and some interminably >> long time before it. >> >> Sadly actual documentation of the u-boot API is a bit thin on the >> ground, but get_timer==ms is also corroborated by some ad-hoc googling I >> did (e.g. resulting in the above link) as well as inspection of some >> random u-boot ports. Some ports have an explicit get_timer_us function, >> which adds credence to the idea that get_timer is in ms instead. > > See also this patch to u-boot upstream: > Ok, I've kept current code as generic and added own timer implementation for raspberry pie > commit 5eaa215607c8668bfa6a7183407eba8fec63d648 > Author: Stephen Warren <swar...@wwwdotorg.org> > Date: Wed Mar 27 18:43:23 2013 +0000 > > ARM: bcm2835: fix get_timer() to return ms > > Apparently, CONFIG_SYS_HZ must be 1000. Change this, and fix the timer > driver to conform to this. > > Have the timer implementation export a custom API get_timer_us() for use > by the BCM2835 MMC API, which needs us resolution for a HW workaround. > > Signed-off-by: Stephen Warren <swar...@wwwdotorg.org> > > and from README: > > - CPU timer options: > CONFIG_SYS_HZ > > The frequency of the timer returned by get_timer(). > get_timer() must operate in milliseconds and this CONFIG > option must be set to 1000. > > Ian. > >
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