On Mon, 16 Jul 2012, Colin Cross wrote:
> vfp_pm_suspend should save the VFP state in suspend after
> any lazy context switch. If it only saves when the VFP is enabled,
> the state can get lost when, on a UP system:
> Thread 1 uses the VFP
> Context switch occurs to thread 2, VFP is disabled but the
> VFP context is not saved
> Thread 2 initiates suspend
> vfp_pm_suspend is called with the VFP disabled, and the unsaved
> VFP context of Thread 1 in the registers
>
> Modify vfp_pm_suspend to save the VFP context whenever
> vfp_current_hw_state is not NULL.
>
> Includes a fix from Ido Yariv <i...@wizery.com>, who pointed out that on
> SMP systems, the state pointer can be pointing to a freed task struct if
> a task exited on another cpu, fixed by using #ifdef CONFIG_SMP in the
> new if clause.
>
> Cc: Russell King <li...@arm.linux.org.uk>
> Cc: Barry Song <b...@csr.com>
> Cc: Catalin Marinas <catalin.mari...@arm.com>
> Cc: Ido Yariv <i...@wizery.com>
> Cc: Daniel Drake <d...@laptop.org>
> Cc: Will Deacon <will.dea...@arm.com>
> Signed-off-by: Colin Cross <ccr...@android.com>
> ---
> arch/arm/vfp/vfpmodule.c | 6 ++++++
> 1 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
> index 58696192..ce55f05 100644
> --- a/arch/arm/vfp/vfpmodule.c
> +++ b/arch/arm/vfp/vfpmodule.c
> @@ -457,6 +457,12 @@ static int vfp_pm_suspend(void)
>
> /* disable, just in case */
> fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
> + } else if (vfp_current_hw_state[ti->cpu]) {
> +#ifndef CONFIG_SMP
> + fmxr(FPEXC, fpexc | FPEXC_EN);
> + vfp_save_state(vfp_current_hw_state[ti->cpu], fpexc);
> + fmxr(FPEXC, fpexc);
> +#endif
> }
Couldn't vfp_sync_hwstate() be used here instead?
Nicolas
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