* Tero Kristo <tero.kristo@xxxxxxxxx> [091119 07:12]:
> From: Tero Kristo <tero.kristo@xxxxxxxxx>
>
> 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.
>
> Main work for this patch was done by Peter and Rajendra. Some cleanup and
> optimization by Tero.
This should go via the linux-arm-kernel@xxxxxxxxxxxxxxxxxxx list.
We should probably merge them both via LAKML as they logically belong
toghether. Can you please resend, and also Cc linux-omap list?
For both, you can add Acked-by: Tony Lindgren <tony@xxxxxxxxxxx>
if you want to.
> Signed-off-by: Tero Kristo <tero.kristo@xxxxxxxxx>
> Cc: Vishwanath Sripathy <vishwanath.bs@xxxxxx>
> Cc: Rajendra Nayak <rnayak@xxxxxx>
> Cc: Richard Woodruff <r-woodruff2@xxxxxx>
> Cc: Peter 'p2' De Schrijver <peter.de-schrijver@xxxxxxxxx>
> ---
> arch/arm/vfp/vfpmodule.c | 25 +++++++++++++++++++++++++
> 1 files changed, 25 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
> index 2d7423a..80a08bd 100644
> --- a/arch/arm/vfp/vfpmodule.c
> +++ b/arch/arm/vfp/vfpmodule.c
> @@ -329,6 +329,31 @@ static void vfp_enable(void *unused)
> #ifdef CONFIG_PM
> #include <linux/sysdev.h>
>
> +void vfp_pm_save_context(void)
> +{
> + struct thread_info *thread = current_thread_info();
> + u32 fpexc = fmrx(FPEXC);
> + __u32 cpu = thread->cpu;
> +
> + if (last_VFP_context[cpu]) {
> + if (!(fpexc & FPEXC_EN)) {
> + /* enable vfp now to save context */
> + vfp_enable(NULL);
> + fmxr(FPEXC, fmrx(FPEXC) | FPEXC_EN);
> + }
> + vfp_save_state(last_VFP_context[cpu], fpexc);
> +
> + /* Disable vfp. The next inst traps an exception and restores*/
> + fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
> +
> + /*
> + * This is needed else the restore might fail if it sees
> + * last_VFP_context if same as the current threads vfp_state.
> + */
> + last_VFP_context[cpu] = NULL;
> + }
> +}
> +
> static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state)
> {
> struct thread_info *ti = current_thread_info();
> --
> 1.5.4.3
>
> --
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