On Thu, 2012-07-19 at 17:21 -0600, Paul Walmsley wrote:
> Hi
>
> On Thu, 19 Jul 2012, Tero Kristo wrote:
>
> > On OMAP4430 HS / EMU chips, ROM code appears to re-configure L4PER domain
> > next powerstate during wakeup from OSWR / OFF, programming it to ON.
> > This will prevent successive entries to cpuidle retention / off, until
> > kernel decices to change the L4PER target state, which can be delayed
> > for a very long time as kernel is lazy programming the target state.
> >
> > This patch fixes the issue within the low power OSWR / OFF mode code, so
> > that this register is saved / restored across MPU OSWR / OFF state.
> >
> > This problem seems to only occur with OMAP4430 HS/EMU, it does not impact
> > OMAP4460+ or GP devices.
> >
> > Signed-off-by: Tero Kristo <t-kri...@ti.com>
> > ---
> > arch/arm/mach-omap2/omap-mpuss-lowpower.c | 39
> > ++++++++++++++++++++++++++++-
> > arch/arm/mach-omap2/pm.h | 1 +
> > arch/arm/mach-omap2/pm44xx.c | 10 +++++++
> > 3 files changed, 49 insertions(+), 1 deletions(-)
> >
> > diff --git a/arch/arm/mach-omap2/omap-mpuss-lowpower.c
> > b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
> > index 0e5f81b..963a61b 100644
> > --- a/arch/arm/mach-omap2/omap-mpuss-lowpower.c
> > +++ b/arch/arm/mach-omap2/omap-mpuss-lowpower.c
>
> ...
>
> > @@ -215,6 +225,28 @@ static void save_l2x0_context(void)
> > {}
> > #endif
> >
> > +static inline void save_l4per_regs(void)
> > +{
> > + int i;
> > +
> > + if (!IS_PM44XX_ERRATUM(PM_OMAP4_ROM_L4PER_ERRATUM_PWSTCT))
> > + return;
> > +
> > + for (i = 0; i < ARRAY_SIZE(l4per_reg); i++)
> > + l4per_reg[i].val = __raw_readl(l4per_reg[i].addr);
>
> This is accessing the system PRM registers directly. We're trying to
> remove these raw register accesses from non-PRM code because a PRM driver
> is in the works. Please move this to prm44xx.c or prminst44xx.c and
> implement a higher-level interface that omap-mpuss-lowpower.c can call.
It looks like this can be dropped out for now completely, I guess I had
a broken PPA on my board which was causing this problem.
-Tero
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