Nishant, > -----Original Message----- > From: Nishanth Menon [mailto:nm@xxxxxx] > Sent: Monday, December 13, 2010 7:13 PM > To: Vishwanath Sripathy > Cc: linux-omap; Eduardo Valentin; Kevin Hilman; Tony Lindgren > Subject: Re: [PATCH 5/5 v3] OMAP3630: PM: Erratum i583: disable > coreoff if < ES1.2 > > Vishwanath Sripathy had written, on 12/13/2010 07:35 AM, the > following: > > Nishant, > > > >> -----Original Message----- > >> From: linux-omap-owner@xxxxxxxxxxxxxxx [mailto:linux-omap- > >> owner@xxxxxxxxxxxxxxx] On Behalf Of Nishanth Menon > >> Sent: Friday, December 03, 2010 10:34 PM > >> To: linux-omap > >> Cc: Eduardo Valentin; Kevin Hilman; Tony Lindgren; Nishanth Menon > >> Subject: [PATCH 5/5 v3] OMAP3630: PM: Erratum i583: disable > coreoff if > >> < ES1.2 > >> > >> From: Eduardo Valentin <eduardo.valentin@xxxxxxxxx> > >> > >> Limitation i583: Self_Refresh Exit issue after OFF mode > >> > >> Issue: > >> When device is waking up from OFF mode, then SDRC state machine > >> sends > >> inappropriate sequence violating JEDEC standards. > >> > >> Impact: > >> OMAP3630 < ES1.2 is impacted as follows depending on the > platform: > >> CS0: for 38.4MHz as internal sysclk, DDR content seen to be stable, > >> while > >> for all other sysclk frequencies, varied levels of instability > >> seen based on varied parameters. > >> CS1: impacted > >> > >> This patch takes option #3 as recommended by the Silicon erratum: > >> Avoid core power domain transitioning to OFF mode. Power > consumption > >> impact is expected in this case. > >> To do this, we route OFF requests to RET request on the impacted > >> revisions > >> of silicon. > >> > >> Cc: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> > >> Cc: Tony Lindgren <tony@xxxxxxxxxxx> > >> > >> [nm@xxxxxx: rebased the code to 2.6.37-rc2- short circuit code > changed > >> a bit] > >> Signed-off-by: Nishanth Menon <nm@xxxxxx> > >> Signed-off-by: Eduardo Valentin <eduardo.valentin@xxxxxxxxx> > >> --- > >> v3: no functional change in erratum wa implementation, just > registration > >> of > >> erratum is collated to a single cpu detection and version check > >> v2: https://patchwork.kernel.org/patch/365262/ > >> rebased to this patch series instead of depending on hs changes > >> fix typo for macro definition > >> v1: http://marc.info/?l=linux-omap&m=129013173425266&w=2 > >> arch/arm/mach-omap2/pm34xx.c | 14 ++++++++++++++ > >> 1 files changed, 14 insertions(+), 0 deletions(-) > >> > >> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach- > >> omap2/pm34xx.c > >> index b49e02b..ba3c0d6 100644 > >> --- a/arch/arm/mach-omap2/pm34xx.c > >> +++ b/arch/arm/mach-omap2/pm34xx.c > >> @@ -56,6 +56,7 @@ > >> #define OMAP343X_CONTROL_REG_VALUE_OFFSET 0xc8 > >> > >> #define RTA_ERRATUM_i608 (1 << 0) > >> +#define SDRC_WAKEUP_ERRATUM_i583 (1 << 1) > >> static u16 pm34xx_errata; > >> #define IS_PM34XX_ERRATUM(id) (pm34xx_errata & (id)) > >> > >> @@ -406,6 +407,17 @@ void omap_sram_idle(void) > >> } > >> > >> /* CORE */ > >> + /* > >> + * Erratum i583: implementation for ES rev < Es1.2 on 3630 > >> + * We cannot enable OFF mode in a stable form for previous > >> + * revisions, transition instead to RET > >> + */ > >> + if (IS_PM34XX_ERRATUM(SDRC_WAKEUP_ERRATUM_i583) && > >> + (core_next_state == PWRDM_POWER_OFF)) { > >> + pwrdm_set_next_pwrst(core_pwrdm, > >> PWRDM_POWER_RET); > >> + core_next_state = PWRDM_POWER_RET; > >> + } > > > > Since next_state in pwrst_list (for core) is not updated, this is throwing > > up an error "Powerdomain (core_pwrdm) didn't enter target state 0" > when > > you off mode is enabled for ES1.1 or lesser (in suspend path). It's not > > really true that Core has not entered target state. It has entered > > Retention state which is the actual target state set in omap_sram_idle. > > However it did not enter the state that was passed by > omap3_pm_suspend. Is > > this expected behavior? > > we could go both ways on this - this patch will(as you noticed) indicate > that the transition failed on <ES1.2, or we could make it entirely > transparent(by modifying the the pwrst_list - claim we achieved off, > while not really hitting off - I personally dont think that is correct. The point I am making is that you cannot distinguish between genuine off /retention failure since this message is thrown for both pass and fail. May be an additional trace message indicating that system entered retention instead of off (for ES<1.2) will be useful. Vishwa > > -- > Regards, > Nishanth Menon -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
