[PATCH 0/2] VFP context save/restore support for OMAP3

[PATCH 0/2] VFP context save/restore support for OMAP3

[Tero Kristo]

From: Tero Kristo <tero.kristo@nokia.com>

These two patches add support for VFP context save and restore. These patches
are a collaboration from several people (listed in CC), I have mainly
split the original patch in two parts (one generic ARM, one for OMAP3 PM),
and optimized the code a bit. No sign-offs added from anybody except myself
at the moment because I have modified the patches quite heavily.

I think patch #1 should actually go to linux-arm list, however I thought to
get some comments about the patches on omap list first.

These will apply on top of PM branch.

-Tero

[PATCH 1/2] ARM: Implemented support for VFP PM context saving

[Tero Kristo]

From: Tero Kristo <tero.kristo@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.

Main work for this patch was done by Peter and Rajendra. Some cleanup and
optimization by Tero.

Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
Cc: Vishwanath Sripathy <vishwanath.bs@ti.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>
Cc: Peter 'p2' De Schrijver <peter.de-schrijver@nokia.com>
---
 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

[PATCH 2/2] OMAP3: Implemented VFP restore/save context

[Tero Kristo]

From: Tero Kristo <tero.kristo@nokia.com>

VFP save context is called before MPU/NEON off. Restore is not needed as
the next VFP trap will restore context automatically. Uses the support
routine implemented in arch/arm/vfp/vfpmodule.c.

Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
Cc: Vishwanath Sripathy <vishwanath.bs@ti.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>
Cc: Peter 'p2' De Schrijver <peter.de-schrijver@nokia.com>
---
 arch/arm/mach-omap2/pm.h     |    1 +
 arch/arm/mach-omap2/pm34xx.c |   21 ++++++++++++++++++++-
 2 files changed, 21 insertions(+), 1 deletions(-)

diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
index 4f22107..dd5bbaf 100644
--- a/arch/arm/mach-omap2/pm.h
+++ b/arch/arm/mach-omap2/pm.h
@@ -18,6 +18,7 @@ extern u32 sleep_while_idle;
 extern u32 voltage_off_while_idle;
 
 extern void *omap3_secure_ram_storage;
+extern void vfp_pm_save_context(void);
 extern void omap3_pm_off_mode_enable(int);
 extern void omap_sram_idle(void);
 extern int omap3_can_sleep(void);
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index b26ae5b..4b01303 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -321,6 +321,18 @@ static void restore_control_register(u32 val)
 	__asm__ __volatile__ ("mcr p15, 0, %0, c1, c0, 0" : : "r" (val));
 }
 
+static inline void omap3_save_neon_context(void)
+{
+#ifdef CONFIG_VFP
+	vfp_pm_save_context();
+#endif
+}
+
+static inline void omap3_restore_neon_context(void)
+{
+	return;
+}
+
 /* Function to restore the table entry that was modified for enabling MMU */
 static void restore_table_entry(void)
 {
@@ -365,6 +377,7 @@ void omap_sram_idle(void)
 	/* save_state = 3 => L1, L2 and logic lost */
 	int save_state = 0;
 	int mpu_next_state = PWRDM_POWER_ON;
+	int neon_next_state = PWRDM_POWER_ON;
 	int per_next_state = PWRDM_POWER_ON;
 	int core_next_state = PWRDM_POWER_ON;
 	int core_prev_state, per_prev_state;
@@ -398,8 +411,12 @@ void omap_sram_idle(void)
 	pwrdm_pre_transition();
 
 	/* NEON control */
-	if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON)
+	if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON) {
 		pwrdm_set_next_pwrst(neon_pwrdm, mpu_next_state);
+		neon_next_state = mpu_next_state;
+		if (neon_next_state == PWRDM_POWER_OFF)
+			omap3_save_neon_context();
+	}
 
 	/* PER */
 	per_next_state = pwrdm_read_next_pwrst(per_pwrdm);
@@ -537,6 +554,8 @@ void omap_sram_idle(void)
 		omap3_disable_io_chain();
 	}
 
+	if (neon_next_state == PWRDM_POWER_OFF)
+		omap3_restore_neon_context();
 
 	pwrdm_post_transition();
 }
-- 
1.5.4.3

Re: [PATCH 1/2] ARM: Implemented support for VFP PM context saving

[Tony Lindgren]

* Tero Kristo <tero.kristo@nokia.com> [091119 07:12]:
> From: Tero Kristo <tero.kristo@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.
> 
> 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@lists.infradead.org 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@atomide.com>
if you want to.

 
> Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
> Cc: Vishwanath Sripathy <vishwanath.bs@ti.com>
> Cc: Rajendra Nayak <rnayak@ti.com>
> Cc: Richard Woodruff <r-woodruff2@ti.com>
> Cc: Peter 'p2' De Schrijver <peter.de-schrijver@nokia.com>
> ---
>  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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Re: [PATCH 2/2] OMAP3: Implemented VFP restore/save context

[Kevin Hilman]

Tero Kristo <tero.kristo@nokia.com> writes:

> From: Tero Kristo <tero.kristo@nokia.com>
>
> VFP save context is called before MPU/NEON off. Restore is not needed as
> the next VFP trap will restore context automatically. Uses the support
> routine implemented in arch/arm/vfp/vfpmodule.c.
>
> Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
> Cc: Vishwanath Sripathy <vishwanath.bs@ti.com>
> Cc: Rajendra Nayak <rnayak@ti.com>
> Cc: Richard Woodruff <r-woodruff2@ti.com>
> Cc: Peter 'p2' De Schrijver <peter.de-schrijver@nokia.com>

Looks good.  I'll queue in PM branch when patch 1/2 is reviewed/accepted on LAKML.

Kevin

> ---
>  arch/arm/mach-omap2/pm.h     |    1 +
>  arch/arm/mach-omap2/pm34xx.c |   21 ++++++++++++++++++++-
>  2 files changed, 21 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
> index 4f22107..dd5bbaf 100644
> --- a/arch/arm/mach-omap2/pm.h
> +++ b/arch/arm/mach-omap2/pm.h
> @@ -18,6 +18,7 @@ extern u32 sleep_while_idle;
>  extern u32 voltage_off_while_idle;
>  
>  extern void *omap3_secure_ram_storage;
> +extern void vfp_pm_save_context(void);
>  extern void omap3_pm_off_mode_enable(int);
>  extern void omap_sram_idle(void);
>  extern int omap3_can_sleep(void);
> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
> index b26ae5b..4b01303 100644
> --- a/arch/arm/mach-omap2/pm34xx.c
> +++ b/arch/arm/mach-omap2/pm34xx.c
> @@ -321,6 +321,18 @@ static void restore_control_register(u32 val)
>  	__asm__ __volatile__ ("mcr p15, 0, %0, c1, c0, 0" : : "r" (val));
>  }
>  
> +static inline void omap3_save_neon_context(void)
> +{
> +#ifdef CONFIG_VFP
> +	vfp_pm_save_context();
> +#endif
> +}
> +
> +static inline void omap3_restore_neon_context(void)
> +{
> +	return;
> +}
> +
>  /* Function to restore the table entry that was modified for enabling MMU */
>  static void restore_table_entry(void)
>  {
> @@ -365,6 +377,7 @@ void omap_sram_idle(void)
>  	/* save_state = 3 => L1, L2 and logic lost */
>  	int save_state = 0;
>  	int mpu_next_state = PWRDM_POWER_ON;
> +	int neon_next_state = PWRDM_POWER_ON;
>  	int per_next_state = PWRDM_POWER_ON;
>  	int core_next_state = PWRDM_POWER_ON;
>  	int core_prev_state, per_prev_state;
> @@ -398,8 +411,12 @@ void omap_sram_idle(void)
>  	pwrdm_pre_transition();
>  
>  	/* NEON control */
> -	if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON)
> +	if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON) {
>  		pwrdm_set_next_pwrst(neon_pwrdm, mpu_next_state);
> +		neon_next_state = mpu_next_state;
> +		if (neon_next_state == PWRDM_POWER_OFF)
> +			omap3_save_neon_context();
> +	}
>  
>  	/* PER */
>  	per_next_state = pwrdm_read_next_pwrst(per_pwrdm);
> @@ -537,6 +554,8 @@ void omap_sram_idle(void)
>  		omap3_disable_io_chain();
>  	}
>  
> +	if (neon_next_state == PWRDM_POWER_OFF)
> +		omap3_restore_neon_context();
>  
>  	pwrdm_post_transition();
>  }
> -- 
> 1.5.4.3
>
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[PATCH 2/2] OMAP3: Implemented VFP restore/save context

[Tero Kristo]

From: Tero Kristo <tero.kristo@nokia.com>

VFP save context is called before MPU/NEON off. Restore is not needed as
the next VFP trap will restore context automatically. Uses the support
routine implemented in arch/arm/vfp/vfpmodule.c.

Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Cc: Vishwanath Sripathy <vishwanath.bs@ti.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>
Cc: Peter 'p2' De Schrijver <peter.de-schrijver@nokia.com>
---
 arch/arm/mach-omap2/pm.h     |    1 +
 arch/arm/mach-omap2/pm34xx.c |   21 ++++++++++++++++++++-
 2 files changed, 21 insertions(+), 1 deletions(-)

diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
index 4f22107..dd5bbaf 100644
--- a/arch/arm/mach-omap2/pm.h
+++ b/arch/arm/mach-omap2/pm.h
@@ -18,6 +18,7 @@ extern u32 sleep_while_idle;
 extern u32 voltage_off_while_idle;
 
 extern void *omap3_secure_ram_storage;
+extern void vfp_pm_save_context(void);
 extern void omap3_pm_off_mode_enable(int);
 extern void omap_sram_idle(void);
 extern int omap3_can_sleep(void);
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index b26ae5b..4b01303 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -321,6 +321,18 @@ static void restore_control_register(u32 val)
 	__asm__ __volatile__ ("mcr p15, 0, %0, c1, c0, 0" : : "r" (val));
 }
 
+static inline void omap3_save_neon_context(void)
+{
+#ifdef CONFIG_VFP
+	vfp_pm_save_context();
+#endif
+}
+
+static inline void omap3_restore_neon_context(void)
+{
+	return;
+}
+
 /* Function to restore the table entry that was modified for enabling MMU */
 static void restore_table_entry(void)
 {
@@ -365,6 +377,7 @@ void omap_sram_idle(void)
 	/* save_state = 3 => L1, L2 and logic lost */
 	int save_state = 0;
 	int mpu_next_state = PWRDM_POWER_ON;
+	int neon_next_state = PWRDM_POWER_ON;
 	int per_next_state = PWRDM_POWER_ON;
 	int core_next_state = PWRDM_POWER_ON;
 	int core_prev_state, per_prev_state;
@@ -398,8 +411,12 @@ void omap_sram_idle(void)
 	pwrdm_pre_transition();
 
 	/* NEON control */
-	if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON)
+	if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON) {
 		pwrdm_set_next_pwrst(neon_pwrdm, mpu_next_state);
+		neon_next_state = mpu_next_state;
+		if (neon_next_state == PWRDM_POWER_OFF)
+			omap3_save_neon_context();
+	}
 
 	/* PER */
 	per_next_state = pwrdm_read_next_pwrst(per_pwrdm);
@@ -537,6 +554,8 @@ void omap_sram_idle(void)
 		omap3_disable_io_chain();
 	}
 
+	if (neon_next_state == PWRDM_POWER_OFF)
+		omap3_restore_neon_context();
 
 	pwrdm_post_transition();
 }
-- 
1.5.4.3

RE: [PATCH 2/2] OMAP3: Implemented VFP restore/save context

[Sripathy, Vishwanath]

> -----Original Message-----
> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-
> owner@vger.kernel.org] On Behalf Of Tero Kristo
> Sent: Tuesday, November 24, 2009 4:07 PM
> To: linux-arm-kernel@lists.infradead.org
> Cc: linux-omap@vger.kernel.org
> Subject: [PATCH 2/2] OMAP3: Implemented VFP restore/save context
> 
> From: Tero Kristo <tero.kristo@nokia.com>
> 
> VFP save context is called before MPU/NEON off. Restore is not needed as
> the next VFP trap will restore context automatically. Uses the support
> routine implemented in arch/arm/vfp/vfpmodule.c.
> 
> Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
> Acked-by: Tony Lindgren <tony@atomide.com>
> Cc: Vishwanath Sripathy <vishwanath.bs@ti.com>
> Cc: Rajendra Nayak <rnayak@ti.com>
> Cc: Richard Woodruff <r-woodruff2@ti.com>
> Cc: Peter 'p2' De Schrijver <peter.de-schrijver@nokia.com>
> ---
>  arch/arm/mach-omap2/pm.h     |    1 +
>  arch/arm/mach-omap2/pm34xx.c |   21 ++++++++++++++++++++-
>  2 files changed, 21 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
> index 4f22107..dd5bbaf 100644
> --- a/arch/arm/mach-omap2/pm.h
> +++ b/arch/arm/mach-omap2/pm.h
> @@ -18,6 +18,7 @@ extern u32 sleep_while_idle;
>  extern u32 voltage_off_while_idle;
> 
>  extern void *omap3_secure_ram_storage;
> +extern void vfp_pm_save_context(void);
>  extern void omap3_pm_off_mode_enable(int);
>  extern void omap_sram_idle(void);
>  extern int omap3_can_sleep(void);
> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
> index b26ae5b..4b01303 100644
> --- a/arch/arm/mach-omap2/pm34xx.c
> +++ b/arch/arm/mach-omap2/pm34xx.c
> @@ -321,6 +321,18 @@ static void restore_control_register(u32 val)
>  	__asm__ __volatile__ ("mcr p15, 0, %0, c1, c0, 0" : : "r" (val));
>  }
> 
> +static inline void omap3_save_neon_context(void)
> +{
> +#ifdef CONFIG_VFP
> +	vfp_pm_save_context();
> +#endif
> +}
> +
> +static inline void omap3_restore_neon_context(void)
> +{
> +	return;
> +}
> +
>  /* Function to restore the table entry that was modified for enabling MMU */
>  static void restore_table_entry(void)
>  {
> @@ -365,6 +377,7 @@ void omap_sram_idle(void)
>  	/* save_state = 3 => L1, L2 and logic lost */
>  	int save_state = 0;
>  	int mpu_next_state = PWRDM_POWER_ON;
> +	int neon_next_state = PWRDM_POWER_ON;
>  	int per_next_state = PWRDM_POWER_ON;
>  	int core_next_state = PWRDM_POWER_ON;
>  	int core_prev_state, per_prev_state;
> @@ -398,8 +411,12 @@ void omap_sram_idle(void)
>  	pwrdm_pre_transition();
> 
>  	/* NEON control */
> -	if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON)
> +	if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON) {
>  		pwrdm_set_next_pwrst(neon_pwrdm, mpu_next_state);
> +		neon_next_state = mpu_next_state;
> +		if (neon_next_state == PWRDM_POWER_OFF)
> +			omap3_save_neon_context();
> +	}
> 
>  	/* PER */
>  	per_next_state = pwrdm_read_next_pwrst(per_pwrdm);
> @@ -537,6 +554,8 @@ void omap_sram_idle(void)
>  		omap3_disable_io_chain();
>  	}
> 
> +	if (neon_next_state == PWRDM_POWER_OFF)
> +		omap3_restore_neon_context();
> 
Why do call restore here when restore is done automatically upon context switch?

>  	pwrdm_post_transition();
>  }
> --
> 1.5.4.3
> 
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RE: [PATCH 2/2] OMAP3: Implemented VFP restore/save context

[Tero.Kristo]

 

>-----Original Message-----
>From: ext Sripathy, Vishwanath [mailto:vishwanath.bs@ti.com] 
>Sent: 24 November, 2009 13:34
>To: Kristo Tero (Nokia-D/Tampere); linux-arm-kernel@lists.infradead.org
>Cc: linux-omap@vger.kernel.org
>Subject: RE: [PATCH 2/2] OMAP3: Implemented VFP restore/save context
>
>
>
>> -----Original Message-----
>> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-
>> owner@vger.kernel.org] On Behalf Of Tero Kristo
>> Sent: Tuesday, November 24, 2009 4:07 PM
>> To: linux-arm-kernel@lists.infradead.org
>> Cc: linux-omap@vger.kernel.org
>> Subject: [PATCH 2/2] OMAP3: Implemented VFP restore/save context
>> 
>> From: Tero Kristo <tero.kristo@nokia.com>
>> 
>> VFP save context is called before MPU/NEON off. Restore is 
>not needed as
>> the next VFP trap will restore context automatically. Uses 
>the support
>> routine implemented in arch/arm/vfp/vfpmodule.c.
>> 
>> Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
>> Acked-by: Tony Lindgren <tony@atomide.com>
>> Cc: Vishwanath Sripathy <vishwanath.bs@ti.com>
>> Cc: Rajendra Nayak <rnayak@ti.com>
>> Cc: Richard Woodruff <r-woodruff2@ti.com>
>> Cc: Peter 'p2' De Schrijver <peter.de-schrijver@nokia.com>
>> ---
>>  arch/arm/mach-omap2/pm.h     |    1 +
>>  arch/arm/mach-omap2/pm34xx.c |   21 ++++++++++++++++++++-
>>  2 files changed, 21 insertions(+), 1 deletions(-)
>> 
>> diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
>> index 4f22107..dd5bbaf 100644
>> --- a/arch/arm/mach-omap2/pm.h
>> +++ b/arch/arm/mach-omap2/pm.h
>> @@ -18,6 +18,7 @@ extern u32 sleep_while_idle;
>>  extern u32 voltage_off_while_idle;
>> 
>>  extern void *omap3_secure_ram_storage;
>> +extern void vfp_pm_save_context(void);
>>  extern void omap3_pm_off_mode_enable(int);
>>  extern void omap_sram_idle(void);
>>  extern int omap3_can_sleep(void);
>> diff --git a/arch/arm/mach-omap2/pm34xx.c 
>b/arch/arm/mach-omap2/pm34xx.c
>> index b26ae5b..4b01303 100644
>> --- a/arch/arm/mach-omap2/pm34xx.c
>> +++ b/arch/arm/mach-omap2/pm34xx.c
>> @@ -321,6 +321,18 @@ static void restore_control_register(u32 val)
>>  	__asm__ __volatile__ ("mcr p15, 0, %0, c1, c0, 0" : : 
>"r" (val));
>>  }
>> 
>> +static inline void omap3_save_neon_context(void)
>> +{
>> +#ifdef CONFIG_VFP
>> +	vfp_pm_save_context();
>> +#endif
>> +}
>> +
>> +static inline void omap3_restore_neon_context(void)
>> +{
>> +	return;
>> +}
>> +
>>  /* Function to restore the table entry that was modified 
>for enabling MMU */
>>  static void restore_table_entry(void)
>>  {
>> @@ -365,6 +377,7 @@ void omap_sram_idle(void)
>>  	/* save_state = 3 => L1, L2 and logic lost */
>>  	int save_state = 0;
>>  	int mpu_next_state = PWRDM_POWER_ON;
>> +	int neon_next_state = PWRDM_POWER_ON;
>>  	int per_next_state = PWRDM_POWER_ON;
>>  	int core_next_state = PWRDM_POWER_ON;
>>  	int core_prev_state, per_prev_state;
>> @@ -398,8 +411,12 @@ void omap_sram_idle(void)
>>  	pwrdm_pre_transition();
>> 
>>  	/* NEON control */
>> -	if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON)
>> +	if (pwrdm_read_pwrst(neon_pwrdm) == PWRDM_POWER_ON) {
>>  		pwrdm_set_next_pwrst(neon_pwrdm, mpu_next_state);
>> +		neon_next_state = mpu_next_state;
>> +		if (neon_next_state == PWRDM_POWER_OFF)
>> +			omap3_save_neon_context();
>> +	}
>> 
>>  	/* PER */
>>  	per_next_state = pwrdm_read_next_pwrst(per_pwrdm);
>> @@ -537,6 +554,8 @@ void omap_sram_idle(void)
>>  		omap3_disable_io_chain();
>>  	}
>> 
>> +	if (neon_next_state == PWRDM_POWER_OFF)
>> +		omap3_restore_neon_context();
>> 
>Why do call restore here when restore is done automatically 
>upon context switch?

That is just a stub if we would need to add something there at some point. restore_neon_context() currently does nothing.


>
>>  	pwrdm_post_transition();
>>  }
>> --
>> 1.5.4.3
>> 
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