On Mon, Oct 27, 2014 at 03:40:31PM -0700, Andrew Morton wrote: > On Mon, 27 Oct 2014 09:09:28 +0100 Johan Hovold <johan@xxxxxxxxxx> wrote: > > > Add new property "ti,system-power-controller" to register the RTC as a > > power-off handler. > > > > Some RTC IP revisions can control an external PMIC via the pmic_power_en > > pin, which can be configured to transition to OFF on ALARM2 events and > > back to ON on subsequent ALARM (wakealarm) events. > > > > This is based on earlier work by Colin Foe-Parker and AnilKumar Ch. [1] > > > > [1] https://www.mail-archive.com/linux-omap@xxxxxxxxxxxxxxx/msg82127.html > > > > Tested-by: Felipe Balbi <balbi@xxxxxx> > > Signed-off-by: Johan Hovold <johan@xxxxxxxxxx> > > --- > > > > Changes since v2: > > - add two-second delay to allow alarm to trigger before returning > > hmpf. As this sentence is below the ^--- it doesn't get into the > changelog. We usually don't keep the patch-revision change log in the commit message (e.g. put in the cover letter). But in general, how do you want to handle updates to a single patch in a series you already have in your tree? Do you prefer a proper incremental-fix patch (with commit message), just an updated single patch, or a resend of the whole series? > > ... > > > > +static void omap_rtc_power_off(void) > > +{ > > + struct omap_rtc *rtc = omap_rtc_power_off_rtc; > > + struct rtc_time tm; > > + unsigned long now; > > + u32 val; > > + > > + /* enable pmic_power_en control */ > > + val = rtc_readl(rtc, OMAP_RTC_PMIC_REG); > > + rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN); > > + > > + /* set alarm two seconds from now */ > > + omap_rtc_read_time_raw(rtc, &tm); > > + bcd2tm(&tm); > > + rtc_tm_to_time(&tm, &now); > > + rtc_time_to_tm(now + 2, &tm); > > + > > + if (tm2bcd(&tm) < 0) { > > + dev_err(&rtc->rtc->dev, "power off failed\n"); > > + return; > > + } > > + > > + rtc_wait_not_busy(rtc); > > + > > + rtc_write(rtc, OMAP_RTC_ALARM2_SECONDS_REG, tm.tm_sec); > > + rtc_write(rtc, OMAP_RTC_ALARM2_MINUTES_REG, tm.tm_min); > > + rtc_write(rtc, OMAP_RTC_ALARM2_HOURS_REG, tm.tm_hour); > > + rtc_write(rtc, OMAP_RTC_ALARM2_DAYS_REG, tm.tm_mday); > > + rtc_write(rtc, OMAP_RTC_ALARM2_MONTHS_REG, tm.tm_mon); > > + rtc_write(rtc, OMAP_RTC_ALARM2_YEARS_REG, tm.tm_year); > > + > > + /* > > + * enable ALARM2 interrupt > > + * > > + * NOTE: this fails on AM3352 if rtc_write (writeb) is used > > + */ > > + val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG); > > + rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG, > > + val | OMAP_RTC_INTERRUPTS_IT_ALARM2); > > + > > + mdelay(2000); > > And it is uncommented. > > How on earth is a reader to know why this is here? The comment above the function reads: * The RTC can be used to control an external PMIC via the pmic_power_en pin, * which can be configured to transition to OFF on ALARM2 events. * * Notes: * The two-second alarm offset is the shortest offset possible as the alarm * registers must be set before the next timer update and the offset * calculation is too heavy for everything to be done within a single access * period (~15us). So it's effect is at least fairly obvious and documented. > I can do this > > --- a/drivers/rtc/rtc-omap.c~rtc-omap-add-support-for-pmic_power_en-v3-fix > +++ a/drivers/rtc/rtc-omap.c > @@ -417,6 +417,7 @@ static void omap_rtc_power_off(void) > rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG, > val | OMAP_RTC_INTERRUPTS_IT_ALARM2); > > + /* Allow alarm to trigger before returning */ > mdelay(2000); > } Looks good, and I should have put something like that there nonetheless. > But it doesn't explain *why* we want the alarm to trigger before > returning. Should we really require every power-off handler to document arch behaviour (even if its inconsistent and currently undocumented); in this case that some arches return to user-space where we may oops if called from process 0 (e.g. systemd, but not if using sysvinit)? Johan -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
