[PATCH 1/4] ARM: OMAP3 PM: Fix IO Daisychain sequence

[Vishwanath Sripathy]

> -----Original Message-----
> From: Paul Walmsley [mailto:paul at pwsan.com]
> Sent: Friday, October 07, 2011 1:50 PM
> To: Vishwanath BS
> Cc: linux-omap at vger.kernel.org; khilman at ti.com; linux-arm-
> kernel at lists.infradead.org
> Subject: Re: [PATCH 1/4] ARM: OMAP3 PM: Fix IO Daisychain sequence
>
> Hi
>
> a few comments:
>
> On Tue, 4 Oct 2011, Vishwanath BS wrote:
>
> > As per OMAP3630 TRM Section 3.5.7.2.2, the right sequence for
> enabling IO Daisy
> > chain is "The I/O wake-up scheme is enabled by triggering the I/O
> daisy chain
> > control (Wu clock) by programming a dedicated register
> > (PRCM.PM_WKEN_WKUP[16] EN_IO_CHAIN) in the PRCM module.Software
> must wait for
> > the I/O daisy chain to complete before it transitions the PER
> domain to a
> > nonfunctional state. This is done by polling a dedicated status
> bit in the PRCM
> > module (PRCM.PM_WKST_WKUP[16] ST_IO_CHAIN). This status bit must
> be cleared by
> > software when the bit is read to  1".
> >
> > The original code was polling on a wrong register which is fixed
> in this patch.
> > Also omap3_enable_io_chain is made non static as it's going to be
> used in
> > subsequent patches.
>
> This patch should be split into a fix (for the WKEN/WKST bug) and
> then a
> new patch that drops the 'static'.  The new patch should also move
> this
> function to prm2xxx_3xxx.c for the same reason that the OMAP4
> version of
> this function should be in prminst44xx.c.
OK, Understood.
>
> In the medium-term, a bunch of the functions from prm2xxx_3xxx.c,
> prminst44xx.c, etc. that are only used by the mach-omap2/pm*.c code
> should
> be moved into the PRM driver that Tero is working on that will live
> in
> drivers/.
OK.
Vishwa
>
> >
> > Signed-off-by: Vishwanath BS <vishwanath.bs at ti.com>
> > ---
> >  arch/arm/mach-omap2/pm.h     |    1 +
> >  arch/arm/mach-omap2/pm34xx.c |    6 +++---
> >  2 files changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
> > index 4e166ad..9a36a7c 100644
> > --- a/arch/arm/mach-omap2/pm.h
> > +++ b/arch/arm/mach-omap2/pm.h
> > @@ -21,6 +21,7 @@ extern void omap_sram_idle(void);
> >  extern int omap3_can_sleep(void);
> >  extern int omap_set_pwrdm_state(struct powerdomain *pwrdm, u32
> state);
> >  extern int omap3_idle_init(void);
> > +extern void omap3_enable_io_chain(void);
> >
> >  #if defined(CONFIG_PM_OPP)
> >  extern int omap3_opp_init(void);
> > diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-
> omap2/pm34xx.c
> > index 7255d9b..61f1a5b 100644
> > --- a/arch/arm/mach-omap2/pm34xx.c
> > +++ b/arch/arm/mach-omap2/pm34xx.c
> > @@ -95,7 +95,7 @@ static inline void
> omap3_per_restore_context(void)
> >  	omap_gpio_restore_context();
> >  }
> >
> > -static void omap3_enable_io_chain(void)
> > +void omap3_enable_io_chain(void)
> >  {
> >  	int timeout = 0;
> >
> > @@ -105,7 +105,7 @@ static void omap3_enable_io_chain(void)
> >  		/* Do a readback to assure write has been done */
> >  		omap2_prm_read_mod_reg(WKUP_MOD, PM_WKEN);
> >
> > -		while (!(omap2_prm_read_mod_reg(WKUP_MOD, PM_WKEN) &
> > +		while (!(omap2_prm_read_mod_reg(WKUP_MOD, PM_WKST) &
> >  			 OMAP3430_ST_IO_CHAIN_MASK)) {
> >  			timeout++;
> >  			if (timeout > 1000) {
> > @@ -114,7 +114,7 @@ static void omap3_enable_io_chain(void)
> >  				return;
> >  			}
> >
> 	omap2_prm_set_mod_reg_bits(OMAP3430_ST_IO_CHAIN_MASK,
> > -					     WKUP_MOD, PM_WKEN);
> > +					     WKUP_MOD, PM_WKST);
> >  		}
> >  	}
> >  }
> > --
> > 1.7.0.4
> >
> > --
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>
>
> - Paul