Messages in this thread Patch in this message | | | Subject | Re: [PATCH] ARM: vfp: Always save VFP state in vfp_pm_suspend | From | Catalin Marinas <> | Date | Mon, 14 Feb 2011 11:42:22 +0000 |
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On Sun, 2011-02-13 at 23:13 +0000, Colin Cross wrote: > vfp_pm_suspend should save the VFP state any time there is > a last_VFP_context. 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 to allow lazy save and restore > Thread 2 initiates suspend > vfp_pm_suspend is called with the VFP disabled, but the > context has not been saved.
At this point is it guaranteed that the thread won't migrate to another CPU? If not, we should use get/put_cpu.
> --- a/arch/arm/vfp/vfpmodule.c > +++ b/arch/arm/vfp/vfpmodule.c > @@ -415,13 +415,12 @@ static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state) > struct thread_info *ti = current_thread_info(); > u32 fpexc = fmrx(FPEXC); > > - /* if vfp is on, then save state for resumption */ > - if (fpexc & FPEXC_EN) { > + /* save state for resume */ > + if (last_VFP_context[ti->cpu]) { > printk(KERN_DEBUG "%s: saving vfp state\n", __func__); > - vfp_save_state(&ti->vfpstate, fpexc); > - > - /* disable, just in case */ > - fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); > + fmxr(FPEXC, fpexc | FPEXC_EN); > + vfp_save_state(last_VFP_context[ti->cpu], fpexc); > + fmxr(FPEXC, fpexc & ~FPEXC_EN); > }
We may want to set the last_VFP_context to NULL so that after resuming (to the same thread) we force the VFP reload from the vfpstate structure. The vfp_support_entry code ignores the reloading if the last_VFP_context is the same as vfpstate.
-- Catalin
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