Dear Walleij, Thanks for your suggest. I will apply your suggest in the next version. Thanks & Regards, S.B. Kim 2011/2/26 Linus Walleij <linux.walleij@xxxxxxxxxx> wrote: > -----Original Message----- > From: linux-samsung-soc-owner@xxxxxxxxxxxxxxx [mailto:linux-samsung-soc- > owner@xxxxxxxxxxxxxxx] On Behalf Of Linus Walleij > Sent: Saturday, February 26, 2011 6:34 PM > To: Sangbeom Kim > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-samsung- > soc@xxxxxxxxxxxxxxx; kgene.kim@xxxxxxxxxxx; ben-linux@xxxxxxxxx > Subject: Re: [PATCH 1/3] ARM: S5P: Add s5p_timer support for HRT > > 2011/2/26 Sangbeom Kim <sbkim73@xxxxxxxxxxx>: > > (...) > > +static void s5p_clockevent_init(void) > > +{ > > + unsigned long pclk; > > + unsigned long clock_rate; > > + unsigned int irq_number; > > + struct clk *tscaler; > > + > > + pclk = clk_get_rate(timerclk); > > + > > + tscaler = clk_get_parent(tdiv_event); > > + > > + clk_set_rate(tscaler, pclk / 2); > > + clk_set_rate(tdiv_event, pclk / 2); > > + clk_set_parent(tin_event, tdiv_event); > > + > > + clock_rate = clk_get_rate(tin_event); > > + clock_count_per_tick = clock_rate / HZ; > > + > > + time_event_device.mult = > > + div_sc(clock_rate, NSEC_PER_SEC, time_event_device.shift); > > + time_event_device.max_delta_ns = > > + clockevent_delta2ns(-1, &time_event_device); > > + time_event_device.min_delta_ns = > > + clockevent_delta2ns(1, &time_event_device); > > This is a very complicated and inprecise way of doing this nowadays. > Skip hardcoding the shift value and calculating mult like that and use > > /* Be able to sleep for atleast 4 seconds (usually more) */ > #define EVT_MIN_RANGE 4 > > clockevents_calc_mult_shift(&time_event_device, > clock_rate, EVT_MIN_RANGE); > > > (...) > > +static void s5p_clocksource_init(void) > > +{ > > + unsigned long pclk; > > + unsigned long clock_rate; > > + > > + pclk = clk_get_rate(timerclk); > > + > > + clk_set_rate(tdiv_source, pclk / 2); > > + clk_set_parent(tin_source, tdiv_source); > > + > > + clock_rate = clk_get_rate(tin_source); > > + > > + s5p_time_setup(timer_source.source_id, TCNT_MAX); > > + s5p_time_start(timer_source.source_id, PERIODIC); > > + > > + if (clocksource_register_hz(&time_clocksource, clock_rate)) > > + panic("%s: can't register clocksource\n", > time_clocksource.name); > > +} > > This is more like it :-) > > But you probably also want to add a sched_clock hook for this > platform too, so you get some nice scheduling resolution. > > I suggest you look at the simple straight-forward driver > for U300 in arch/arm/mach-u300/timer.c for inspiration. > It's using the same timer that is used for clocksource for > sched_clock(). > > > Yours, > Linus Walleij > -- > To unsubscribe from this list: send the line "unsubscribe linux-samsung- > soc" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
 |