[PATCHv2 1/2] ARM: VFP: Fixed suspend and added context save support

[Tony Lindgren]

* ye janboe <janboe.ye at gmail.com> [100510 20:10]:
> hi, Russell, Tony
> 
> Is this patch ignored by you? I do not see any ack for this patch.

I guess we're still waiting to hear from Russell. AFAIK, this is needed
in addition to the three patches from Imre.

Acked-by: Tony Lindgren <tony at atomide.com>
 
> Thanks
> 
> Janboe Ye
> 
> 2009/12/3 Tero Kristo <tero.kristo at nokia.com>:
> > From: Tero Kristo <tero.kristo at nokia.com>
> >
> > In some ARM architectures, like OMAP3, the VFP context can be lost during
> > dynamic sleep cycle. For this purpose, there is now a function
> > vfp_pm_save_context() that should be called before the VFP is assumed to
> > lose context. Next VFP trap will then restore context automatically.
> >
> > We need to have the last_VFP_context[cpu] cleared after the save in idle,
> > else the restore would fail to restore when it sees that the last_VFP_context
> > is same as the current threads vfp_state. This happens when the same
> > process/thread traps an exception post idle.
> >
> > This patch also fixes a potential problem with vfp_pm_suspend(), where
> > VFP context can be lost if the current process does not have VFP enabled.
> > Fixed by calling vfp_pm_save_context().
> >
> > Signed-off-by: Tero Kristo <tero.kristo at nokia.com>
> > Cc: Vishwanath Sripathy <vishwanath.bs at ti.com>
> > Cc: Rajendra Nayak <rnayak at ti.com>
> > Cc: Richard Woodruff <r-woodruff2 at ti.com>
> > Cc: Peter 'p2' De Schrijver <peter.de-schrijver at nokia.com>
> > ---
> >  arch/arm/vfp/vfpmodule.c |   28 ++++++++++++++++++++--------
> >  1 files changed, 20 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
> > index 2d7423a..920a33b 100644
> > --- a/arch/arm/vfp/vfpmodule.c
> > +++ b/arch/arm/vfp/vfpmodule.c
> > @@ -329,22 +329,34 @@ static void vfp_enable(void *unused)
> >  #ifdef CONFIG_PM
> >  #include <linux/sysdev.h>
> >
> > -static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state)
> > +void vfp_pm_save_context(void)
> >  {
> > -       struct thread_info *ti = current_thread_info();
> >        u32 fpexc = fmrx(FPEXC);
> > +       unsigned int cpu = get_cpu();
> > +
> > +       /* Save last_VFP_context if needed */
> > +       if (last_VFP_context[cpu]) {
> > +               /* Enable vfp to save context */
> > +               if (!(fpexc & FPEXC_EN)) {
> > +                       vfp_enable(NULL);
> > +                       fmxr(FPEXC, fpexc | FPEXC_EN);
> > +               }
> >
> > -       /* if vfp is on, then save state for resumption */
> > -       if (fpexc & FPEXC_EN) {
> >                printk(KERN_DEBUG "%s: saving vfp state\n", __func__);
> > -               vfp_save_state(&ti->vfpstate, fpexc);
> > +               vfp_save_state(last_VFP_context[cpu], fpexc);
> >
> >                /* disable, just in case */
> > -               fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
> > +               fmxr(FPEXC, fpexc & ~FPEXC_EN);
> > +
> > +               last_VFP_context[cpu] = NULL;
> >        }
> >
> > -       /* clear any information we had about last context state */
> > -       memset(last_VFP_context, 0, sizeof(last_VFP_context));
> > +       put_cpu();
> > +}
> > +
> > +static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state)
> > +{
> > +       vfp_pm_save_context();
> >
> >        return 0;
> >  }
> > --
> > 1.5.4.3
> >
> > --
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