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

[ye janboe]

hi, Russell, Tony

Is this patch ignored by you? I do not see any ack for this patch.

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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