[PATCH v4] ARM: vfp: Always save VFP state in vfp_pm_suspend

[PATCH v4] ARM: vfp: Always save VFP state in vfp_pm_suspend

[Barry Song]

From: Colin Cross <ccross@android.com>

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.

Modify vfp_pm_suspend to save the VFP context whenever
last_VFP_context is set.

Signed-off-by: Colin Cross <ccross@android.com>
Cc: Binghua Duan <binghua.duan@csr.com>
Signed-off-by: Rongjun Ying <rongjun.ying@csr.com>
Signed-off-by: Barry Song <21cnbao@gmail.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm/vfp/vfpmodule.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index f746950..e6fe6ae 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -412,6 +412,10 @@ static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state)
 
 		/* disable, just in case */
 		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
+	} else if (last_VFP_context[ti->cpu]) {
+		fmxr(FPEXC, fpexc | FPEXC_EN);
+		vfp_save_state(last_VFP_context[ti->cpu], fpexc);
+		fmxr(FPEXC, fpexc);
 	}
 
 	/* clear any information we had about last context state */
-- 
1.6.0.4

[PATCH v4] ARM: vfp: Always save VFP state in vfp_pm_suspend

[Barry Song]

Any update for this?

2011/5/10 Barry Song <21cnbao@gmail.com>:
> From: Colin Cross <ccross@android.com>
>
> 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.
>
> Modify vfp_pm_suspend to save the VFP context whenever
> last_VFP_context is set.
>
> Signed-off-by: Colin Cross <ccross@android.com>
> Cc: Binghua Duan <binghua.duan@csr.com>
> Signed-off-by: Rongjun Ying <rongjun.ying@csr.com>
> Signed-off-by: Barry Song <21cnbao@gmail.com>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> ---
> ?arch/arm/vfp/vfpmodule.c | ? ?4 ++++
> ?1 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
> index f746950..e6fe6ae 100644
> --- a/arch/arm/vfp/vfpmodule.c
> +++ b/arch/arm/vfp/vfpmodule.c
> @@ -412,6 +412,10 @@ static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state)
>
> ? ? ? ? ? ? ? ?/* disable, just in case */
> ? ? ? ? ? ? ? ?fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
> + ? ? ? } else if (last_VFP_context[ti->cpu]) {
> + ? ? ? ? ? ? ? fmxr(FPEXC, fpexc | FPEXC_EN);
> + ? ? ? ? ? ? ? vfp_save_state(last_VFP_context[ti->cpu], fpexc);
> + ? ? ? ? ? ? ? fmxr(FPEXC, fpexc);
> ? ? ? ?}
>
> ? ? ? ?/* clear any information we had about last context state */
> --
> 1.6.0.4
>
>

[PATCH v4] ARM: vfp: Always save VFP state in vfp_pm_suspend

[Barry Song]

this patch has been reviewed by Catalin Marinas for a long time. but
why isn't there any feedback by now?
it actually is a very useful fix to vfp PM.

2011/5/19 Barry Song <21cnbao@gmail.com>:
> Any update for this?
>
> 2011/5/10 Barry Song <21cnbao@gmail.com>:
>> From: Colin Cross <ccross@android.com>
>>
>> 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.
>>
>> Modify vfp_pm_suspend to save the VFP context whenever
>> last_VFP_context is set.
>>
>> Signed-off-by: Colin Cross <ccross@android.com>
>> Cc: Binghua Duan <binghua.duan@csr.com>
>> Signed-off-by: Rongjun Ying <rongjun.ying@csr.com>
>> Signed-off-by: Barry Song <21cnbao@gmail.com>
>> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
>> ---
>> ?arch/arm/vfp/vfpmodule.c | ? ?4 ++++
>> ?1 files changed, 4 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
>> index f746950..e6fe6ae 100644
>> --- a/arch/arm/vfp/vfpmodule.c
>> +++ b/arch/arm/vfp/vfpmodule.c
>> @@ -412,6 +412,10 @@ static int vfp_pm_suspend(struct sys_device *dev, pm_message_t state)
>>
>> ? ? ? ? ? ? ? ?/* disable, just in case */
>> ? ? ? ? ? ? ? ?fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
>> + ? ? ? } else if (last_VFP_context[ti->cpu]) {
>> + ? ? ? ? ? ? ? fmxr(FPEXC, fpexc | FPEXC_EN);
>> + ? ? ? ? ? ? ? vfp_save_state(last_VFP_context[ti->cpu], fpexc);
>> + ? ? ? ? ? ? ? fmxr(FPEXC, fpexc);
>> ? ? ? ?}
>>
>> ? ? ? ?/* clear any information we had about last context state */
>> --
>> 1.6.0.4