[PATCH 0/2] Make Tegra cpuidle driver PSCI compatible

[PATCH 0/2] Make Tegra cpuidle driver PSCI compatible

[Jan Kiszka]

Two small patches so that we can keep the Tegra cpuidle driver enabled
even in the presence of PSCI which takes over some duties (U-Boot is
about to gain such support for Tegra124).

Jan

Jan Kiszka (2):
  ARM: Availability of psci_smp_available depends on CONFIG_SMP
  ARM: tegra: Disable cpuidle driver if PSCI is present

 arch/arm/include/asm/psci.h | 6 +++++-
 arch/arm/mach-tegra/Kconfig | 1 +
 arch/arm/mach-tegra/tegra.c | 4 +++-
 3 files changed, 9 insertions(+), 2 deletions(-)

-- 
2.1.4

[PATCH 0/2] Make Tegra cpuidle driver PSCI compatible

[Jan Kiszka]

Two small patches so that we can keep the Tegra cpuidle driver enabled
even in the presence of PSCI which takes over some duties (U-Boot is
about to gain such support for Tegra124).

Jan

Jan Kiszka (2):
  ARM: Availability of psci_smp_available depends on CONFIG_SMP
  ARM: tegra: Disable cpuidle driver if PSCI is present

 arch/arm/include/asm/psci.h | 6 +++++-
 arch/arm/mach-tegra/Kconfig | 1 +
 arch/arm/mach-tegra/tegra.c | 4 +++-
 3 files changed, 9 insertions(+), 2 deletions(-)

-- 
2.1.4

[PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Jan Kiszka]

Ensure that we can use psci_smp_available without checking for
CONFIG_SMP first.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 arch/arm/include/asm/psci.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
index c25ef3e..eef6a0a 100644
--- a/arch/arm/include/asm/psci.h
+++ b/arch/arm/include/asm/psci.h
@@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
 
 #ifdef CONFIG_ARM_PSCI
 int psci_init(void);
-bool psci_smp_available(void);
 #else
 static inline int psci_init(void) { return 0; }
+#endif
+
+#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
+bool psci_smp_available(void);
+#else
 static inline bool psci_smp_available(void) { return false; }
 #endif
 
-- 
2.1.4

[PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Jan Kiszka]

Ensure that we can use psci_smp_available without checking for
CONFIG_SMP first.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 arch/arm/include/asm/psci.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
index c25ef3e..eef6a0a 100644
--- a/arch/arm/include/asm/psci.h
+++ b/arch/arm/include/asm/psci.h
@@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
 
 #ifdef CONFIG_ARM_PSCI
 int psci_init(void);
-bool psci_smp_available(void);
 #else
 static inline int psci_init(void) { return 0; }
+#endif
+
+#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
+bool psci_smp_available(void);
+#else
 static inline bool psci_smp_available(void) { return false; }
 #endif
 
-- 
2.1.4

[PATCH 2/2] ARM: tegra: Disable cpuidle driver if PSCI is present

[Jan Kiszka]

The firmware takes over the ownership of the flow controller when it
provides PSCI support. To avoid clashes, disable the Tegra cpuidle
driver if PSCI was detected.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 arch/arm/mach-tegra/Kconfig | 1 +
 arch/arm/mach-tegra/tegra.c | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index 5d1a318..f93e4dc 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -4,6 +4,7 @@ menuconfig ARCH_TEGRA
 	select ARCH_SUPPORTS_TRUSTED_FOUNDATIONS
 	select ARM_AMBA
 	select ARM_GIC
+	select ARM_PSCI
 	select CLKSRC_MMIO
 	select HAVE_ARM_SCU if SMP
 	select HAVE_ARM_TWD if SMP
diff --git a/arch/arm/mach-tegra/tegra.c b/arch/arm/mach-tegra/tegra.c
index 861d884..17e1adc 100644
--- a/arch/arm/mach-tegra/tegra.c
+++ b/arch/arm/mach-tegra/tegra.c
@@ -44,6 +44,7 @@
 #include <asm/mach-types.h>
 #include <asm/setup.h>
 #include <asm/trusted_foundations.h>
+#include <asm/psci.h>
 
 #include "board.h"
 #include "common.h"
@@ -136,7 +137,8 @@ static void __init tegra_dt_init_late(void)
 	int i;
 
 	tegra_init_suspend();
-	tegra_cpuidle_init();
+	if (!psci_smp_available())
+		tegra_cpuidle_init();
 
 	for (i = 0; i < ARRAY_SIZE(board_init_funcs); i++) {
 		if (of_machine_is_compatible(board_init_funcs[i].machine)) {
-- 
2.1.4

[PATCH 2/2] ARM: tegra: Disable cpuidle driver if PSCI is present

[Jan Kiszka]

The firmware takes over the ownership of the flow controller when it
provides PSCI support. To avoid clashes, disable the Tegra cpuidle
driver if PSCI was detected.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 arch/arm/mach-tegra/Kconfig | 1 +
 arch/arm/mach-tegra/tegra.c | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index 5d1a318..f93e4dc 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -4,6 +4,7 @@ menuconfig ARCH_TEGRA
 	select ARCH_SUPPORTS_TRUSTED_FOUNDATIONS
 	select ARM_AMBA
 	select ARM_GIC
+	select ARM_PSCI
 	select CLKSRC_MMIO
 	select HAVE_ARM_SCU if SMP
 	select HAVE_ARM_TWD if SMP
diff --git a/arch/arm/mach-tegra/tegra.c b/arch/arm/mach-tegra/tegra.c
index 861d884..17e1adc 100644
--- a/arch/arm/mach-tegra/tegra.c
+++ b/arch/arm/mach-tegra/tegra.c
@@ -44,6 +44,7 @@
 #include <asm/mach-types.h>
 #include <asm/setup.h>
 #include <asm/trusted_foundations.h>
+#include <asm/psci.h>
 
 #include "board.h"
 #include "common.h"
@@ -136,7 +137,8 @@ static void __init tegra_dt_init_late(void)
 	int i;
 
 	tegra_init_suspend();
-	tegra_cpuidle_init();
+	if (!psci_smp_available())
+		tegra_cpuidle_init();
 
 	for (i = 0; i < ARRAY_SIZE(board_init_funcs); i++) {
 		if (of_machine_is_compatible(board_init_funcs[i].machine)) {
-- 
2.1.4

Re: [PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 1110 bytes --]

On Fri, May 08, 2015 at 07:55:26AM +0200, Jan Kiszka wrote:
> Ensure that we can use psci_smp_available without checking for
> CONFIG_SMP first.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org>
> ---
>  arch/arm/include/asm/psci.h | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> index c25ef3e..eef6a0a 100644
> --- a/arch/arm/include/asm/psci.h
> +++ b/arch/arm/include/asm/psci.h
> @@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
>  
>  #ifdef CONFIG_ARM_PSCI
>  int psci_init(void);
> -bool psci_smp_available(void);
>  #else
>  static inline int psci_init(void) { return 0; }
> +#endif
> +
> +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
> +bool psci_smp_available(void);
> +#else
>  static inline bool psci_smp_available(void) { return false; }
>  #endif
>  

Looks good to me.

Russell, would you be willing to ack this patch so that I can take it
through the Tegra tree along with patch 2/2 that depends on this?

Thierry

[-- Attachment #2: Type: application/pgp-signature, Size: 819 bytes --]

[PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Thierry Reding]

On Fri, May 08, 2015 at 07:55:26AM +0200, Jan Kiszka wrote:
> Ensure that we can use psci_smp_available without checking for
> CONFIG_SMP first.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  arch/arm/include/asm/psci.h | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> index c25ef3e..eef6a0a 100644
> --- a/arch/arm/include/asm/psci.h
> +++ b/arch/arm/include/asm/psci.h
> @@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
>  
>  #ifdef CONFIG_ARM_PSCI
>  int psci_init(void);
> -bool psci_smp_available(void);
>  #else
>  static inline int psci_init(void) { return 0; }
> +#endif
> +
> +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
> +bool psci_smp_available(void);
> +#else
>  static inline bool psci_smp_available(void) { return false; }
>  #endif
>  

Looks good to me.

Russell, would you be willing to ack this patch so that I can take it
through the Tegra tree along with patch 2/2 that depends on this?

Thierry
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Re: [PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Russell King - ARM Linux]

On Fri, May 08, 2015 at 01:26:17PM +0200, Thierry Reding wrote:
> On Fri, May 08, 2015 at 07:55:26AM +0200, Jan Kiszka wrote:
> > Ensure that we can use psci_smp_available without checking for
> > CONFIG_SMP first.
> > 
> > Signed-off-by: Jan Kiszka <jan.kiszka-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org>
> > ---
> >  arch/arm/include/asm/psci.h | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> > index c25ef3e..eef6a0a 100644
> > --- a/arch/arm/include/asm/psci.h
> > +++ b/arch/arm/include/asm/psci.h
> > @@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
> >  
> >  #ifdef CONFIG_ARM_PSCI
> >  int psci_init(void);
> > -bool psci_smp_available(void);
> >  #else
> >  static inline int psci_init(void) { return 0; }
> > +#endif
> > +
> > +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
> > +bool psci_smp_available(void);
> > +#else
> >  static inline bool psci_smp_available(void) { return false; }
> >  #endif
> >  
> 
> Looks good to me.
> 
> Russell, would you be willing to ack this patch so that I can take it
> through the Tegra tree along with patch 2/2 that depends on this?

I'd prefer to see an ack from Will on this, as it's code which Will
contributed and presumably understands better than me.

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.

[PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Russell King - ARM Linux]

On Fri, May 08, 2015 at 01:26:17PM +0200, Thierry Reding wrote:
> On Fri, May 08, 2015 at 07:55:26AM +0200, Jan Kiszka wrote:
> > Ensure that we can use psci_smp_available without checking for
> > CONFIG_SMP first.
> > 
> > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> > ---
> >  arch/arm/include/asm/psci.h | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> > index c25ef3e..eef6a0a 100644
> > --- a/arch/arm/include/asm/psci.h
> > +++ b/arch/arm/include/asm/psci.h
> > @@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
> >  
> >  #ifdef CONFIG_ARM_PSCI
> >  int psci_init(void);
> > -bool psci_smp_available(void);
> >  #else
> >  static inline int psci_init(void) { return 0; }
> > +#endif
> > +
> > +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
> > +bool psci_smp_available(void);
> > +#else
> >  static inline bool psci_smp_available(void) { return false; }
> >  #endif
> >  
> 
> Looks good to me.
> 
> Russell, would you be willing to ack this patch so that I can take it
> through the Tegra tree along with patch 2/2 that depends on this?

I'd prefer to see an ack from Will on this, as it's code which Will
contributed and presumably understands better than me.

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.

Re: [PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Will Deacon]

On Fri, May 08, 2015 at 03:56:20PM +0100, Russell King - ARM Linux wrote:
> On Fri, May 08, 2015 at 01:26:17PM +0200, Thierry Reding wrote:
> > On Fri, May 08, 2015 at 07:55:26AM +0200, Jan Kiszka wrote:
> > > Ensure that we can use psci_smp_available without checking for
> > > CONFIG_SMP first.
> > > 
> > > Signed-off-by: Jan Kiszka <jan.kiszka-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org>
> > > ---
> > >  arch/arm/include/asm/psci.h | 6 +++++-
> > >  1 file changed, 5 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> > > index c25ef3e..eef6a0a 100644
> > > --- a/arch/arm/include/asm/psci.h
> > > +++ b/arch/arm/include/asm/psci.h
> > > @@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
> > >  
> > >  #ifdef CONFIG_ARM_PSCI
> > >  int psci_init(void);
> > > -bool psci_smp_available(void);
> > >  #else
> > >  static inline int psci_init(void) { return 0; }
> > > +#endif
> > > +
> > > +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
> > > +bool psci_smp_available(void);
> > > +#else
> > >  static inline bool psci_smp_available(void) { return false; }
> > >  #endif
> > >  
> > 
> > Looks good to me.
> > 
> > Russell, would you be willing to ack this patch so that I can take it
> > through the Tegra tree along with patch 2/2 that depends on this?
> 
> I'd prefer to see an ack from Will on this, as it's code which Will
> contributed and presumably understands better than me.

Sorry, I'm late to the thread so I'm a tad confused.

If I understand correctly, these two patches are trying to avoid using
the tegra cpuidle driver if PSCI is available instead? That raises the
question as to whether or not you're actually trying to discover whether
you're in the secure or non-secure world.

I assume PSCI only works if the kernel is running in non-secure mode,
but does the Tegra cpuidle driver only work in secure mode?

Will

[PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Will Deacon]

On Fri, May 08, 2015 at 03:56:20PM +0100, Russell King - ARM Linux wrote:
> On Fri, May 08, 2015 at 01:26:17PM +0200, Thierry Reding wrote:
> > On Fri, May 08, 2015 at 07:55:26AM +0200, Jan Kiszka wrote:
> > > Ensure that we can use psci_smp_available without checking for
> > > CONFIG_SMP first.
> > > 
> > > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> > > ---
> > >  arch/arm/include/asm/psci.h | 6 +++++-
> > >  1 file changed, 5 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> > > index c25ef3e..eef6a0a 100644
> > > --- a/arch/arm/include/asm/psci.h
> > > +++ b/arch/arm/include/asm/psci.h
> > > @@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
> > >  
> > >  #ifdef CONFIG_ARM_PSCI
> > >  int psci_init(void);
> > > -bool psci_smp_available(void);
> > >  #else
> > >  static inline int psci_init(void) { return 0; }
> > > +#endif
> > > +
> > > +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
> > > +bool psci_smp_available(void);
> > > +#else
> > >  static inline bool psci_smp_available(void) { return false; }
> > >  #endif
> > >  
> > 
> > Looks good to me.
> > 
> > Russell, would you be willing to ack this patch so that I can take it
> > through the Tegra tree along with patch 2/2 that depends on this?
> 
> I'd prefer to see an ack from Will on this, as it's code which Will
> contributed and presumably understands better than me.

Sorry, I'm late to the thread so I'm a tad confused.

If I understand correctly, these two patches are trying to avoid using
the tegra cpuidle driver if PSCI is available instead? That raises the
question as to whether or not you're actually trying to discover whether
you're in the secure or non-secure world.

I assume PSCI only works if the kernel is running in non-secure mode,
but does the Tegra cpuidle driver only work in secure mode?

Will

Re: [PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Jan Kiszka]

On 2015-05-08 18:14, Will Deacon wrote:
> On Fri, May 08, 2015 at 03:56:20PM +0100, Russell King - ARM Linux wrote:
>> On Fri, May 08, 2015 at 01:26:17PM +0200, Thierry Reding wrote:
>>> On Fri, May 08, 2015 at 07:55:26AM +0200, Jan Kiszka wrote:
>>>> Ensure that we can use psci_smp_available without checking for
>>>> CONFIG_SMP first.
>>>>
>>>> Signed-off-by: Jan Kiszka <jan.kiszka-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org>
>>>> ---
>>>>  arch/arm/include/asm/psci.h | 6 +++++-
>>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
>>>> index c25ef3e..eef6a0a 100644
>>>> --- a/arch/arm/include/asm/psci.h
>>>> +++ b/arch/arm/include/asm/psci.h
>>>> @@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
>>>>  
>>>>  #ifdef CONFIG_ARM_PSCI
>>>>  int psci_init(void);
>>>> -bool psci_smp_available(void);
>>>>  #else
>>>>  static inline int psci_init(void) { return 0; }
>>>> +#endif
>>>> +
>>>> +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
>>>> +bool psci_smp_available(void);
>>>> +#else
>>>>  static inline bool psci_smp_available(void) { return false; }
>>>>  #endif
>>>>  
>>>
>>> Looks good to me.
>>>
>>> Russell, would you be willing to ack this patch so that I can take it
>>> through the Tegra tree along with patch 2/2 that depends on this?
>>
>> I'd prefer to see an ack from Will on this, as it's code which Will
>> contributed and presumably understands better than me.
> 
> Sorry, I'm late to the thread so I'm a tad confused.
> 
> If I understand correctly, these two patches are trying to avoid using
> the tegra cpuidle driver if PSCI is available instead? That raises the
> question as to whether or not you're actually trying to discover whether
> you're in the secure or non-secure world.
> 
> I assume PSCI only works if the kernel is running in non-secure mode,
> but does the Tegra cpuidle driver only work in secure mode?

To my understanding of the hardware, the flow controller can be accessed
from both worlds. So, testing the mode would neither be sufficient nor
more logical - it's PSCI which occupies this resource, not automatically
all secure monitors.

Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux

[PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Jan Kiszka]

On 2015-05-08 18:14, Will Deacon wrote:
> On Fri, May 08, 2015 at 03:56:20PM +0100, Russell King - ARM Linux wrote:
>> On Fri, May 08, 2015 at 01:26:17PM +0200, Thierry Reding wrote:
>>> On Fri, May 08, 2015 at 07:55:26AM +0200, Jan Kiszka wrote:
>>>> Ensure that we can use psci_smp_available without checking for
>>>> CONFIG_SMP first.
>>>>
>>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>>> ---
>>>>  arch/arm/include/asm/psci.h | 6 +++++-
>>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
>>>> index c25ef3e..eef6a0a 100644
>>>> --- a/arch/arm/include/asm/psci.h
>>>> +++ b/arch/arm/include/asm/psci.h
>>>> @@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
>>>>  
>>>>  #ifdef CONFIG_ARM_PSCI
>>>>  int psci_init(void);
>>>> -bool psci_smp_available(void);
>>>>  #else
>>>>  static inline int psci_init(void) { return 0; }
>>>> +#endif
>>>> +
>>>> +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
>>>> +bool psci_smp_available(void);
>>>> +#else
>>>>  static inline bool psci_smp_available(void) { return false; }
>>>>  #endif
>>>>  
>>>
>>> Looks good to me.
>>>
>>> Russell, would you be willing to ack this patch so that I can take it
>>> through the Tegra tree along with patch 2/2 that depends on this?
>>
>> I'd prefer to see an ack from Will on this, as it's code which Will
>> contributed and presumably understands better than me.
> 
> Sorry, I'm late to the thread so I'm a tad confused.
> 
> If I understand correctly, these two patches are trying to avoid using
> the tegra cpuidle driver if PSCI is available instead? That raises the
> question as to whether or not you're actually trying to discover whether
> you're in the secure or non-secure world.
> 
> I assume PSCI only works if the kernel is running in non-secure mode,
> but does the Tegra cpuidle driver only work in secure mode?

To my understanding of the hardware, the flow controller can be accessed
from both worlds. So, testing the mode would neither be sufficient nor
more logical - it's PSCI which occupies this resource, not automatically
all secure monitors.

Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux

Re: [PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Peter De Schrijver]

On Sun, May 10, 2015 at 11:48:20AM +0200, Jan Kiszka wrote:
> On 2015-05-08 18:14, Will Deacon wrote:
> > On Fri, May 08, 2015 at 03:56:20PM +0100, Russell King - ARM Linux wrote:
> >> On Fri, May 08, 2015 at 01:26:17PM +0200, Thierry Reding wrote:
> >>> On Fri, May 08, 2015 at 07:55:26AM +0200, Jan Kiszka wrote:
> >>>> Ensure that we can use psci_smp_available without checking for
> >>>> CONFIG_SMP first.
> >>>>
> >>>> Signed-off-by: Jan Kiszka <jan.kiszka-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org>
> >>>> ---
> >>>>  arch/arm/include/asm/psci.h | 6 +++++-
> >>>>  1 file changed, 5 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> >>>> index c25ef3e..eef6a0a 100644
> >>>> --- a/arch/arm/include/asm/psci.h
> >>>> +++ b/arch/arm/include/asm/psci.h
> >>>> @@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
> >>>>  
> >>>>  #ifdef CONFIG_ARM_PSCI
> >>>>  int psci_init(void);
> >>>> -bool psci_smp_available(void);
> >>>>  #else
> >>>>  static inline int psci_init(void) { return 0; }
> >>>> +#endif
> >>>> +
> >>>> +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
> >>>> +bool psci_smp_available(void);
> >>>> +#else
> >>>>  static inline bool psci_smp_available(void) { return false; }
> >>>>  #endif
> >>>>  
> >>>
> >>> Looks good to me.
> >>>
> >>> Russell, would you be willing to ack this patch so that I can take it
> >>> through the Tegra tree along with patch 2/2 that depends on this?
> >>
> >> I'd prefer to see an ack from Will on this, as it's code which Will
> >> contributed and presumably understands better than me.
> > 
> > Sorry, I'm late to the thread so I'm a tad confused.
> > 
> > If I understand correctly, these two patches are trying to avoid using
> > the tegra cpuidle driver if PSCI is available instead? That raises the
> > question as to whether or not you're actually trying to discover whether
> > you're in the secure or non-secure world.
> > 
> > I assume PSCI only works if the kernel is running in non-secure mode,
> > but does the Tegra cpuidle driver only work in secure mode?
> 
> To my understanding of the hardware, the flow controller can be accessed
> from both worlds. So, testing the mode would neither be sufficient nor
> more logical - it's PSCI which occupies this resource, not automatically
> all secure monitors.

This is correct. The flow controller doesn't check the NS bit.

Cheers,

Peter.

[PATCH 1/2] ARM: Availability of psci_smp_available depends on CONFIG_SMP

[Peter De Schrijver]

On Sun, May 10, 2015 at 11:48:20AM +0200, Jan Kiszka wrote:
> On 2015-05-08 18:14, Will Deacon wrote:
> > On Fri, May 08, 2015 at 03:56:20PM +0100, Russell King - ARM Linux wrote:
> >> On Fri, May 08, 2015 at 01:26:17PM +0200, Thierry Reding wrote:
> >>> On Fri, May 08, 2015 at 07:55:26AM +0200, Jan Kiszka wrote:
> >>>> Ensure that we can use psci_smp_available without checking for
> >>>> CONFIG_SMP first.
> >>>>
> >>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> >>>> ---
> >>>>  arch/arm/include/asm/psci.h | 6 +++++-
> >>>>  1 file changed, 5 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> >>>> index c25ef3e..eef6a0a 100644
> >>>> --- a/arch/arm/include/asm/psci.h
> >>>> +++ b/arch/arm/include/asm/psci.h
> >>>> @@ -39,9 +39,13 @@ extern struct smp_operations psci_smp_ops;
> >>>>  
> >>>>  #ifdef CONFIG_ARM_PSCI
> >>>>  int psci_init(void);
> >>>> -bool psci_smp_available(void);
> >>>>  #else
> >>>>  static inline int psci_init(void) { return 0; }
> >>>> +#endif
> >>>> +
> >>>> +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_SMP)
> >>>> +bool psci_smp_available(void);
> >>>> +#else
> >>>>  static inline bool psci_smp_available(void) { return false; }
> >>>>  #endif
> >>>>  
> >>>
> >>> Looks good to me.
> >>>
> >>> Russell, would you be willing to ack this patch so that I can take it
> >>> through the Tegra tree along with patch 2/2 that depends on this?
> >>
> >> I'd prefer to see an ack from Will on this, as it's code which Will
> >> contributed and presumably understands better than me.
> > 
> > Sorry, I'm late to the thread so I'm a tad confused.
> > 
> > If I understand correctly, these two patches are trying to avoid using
> > the tegra cpuidle driver if PSCI is available instead? That raises the
> > question as to whether or not you're actually trying to discover whether
> > you're in the secure or non-secure world.
> > 
> > I assume PSCI only works if the kernel is running in non-secure mode,
> > but does the Tegra cpuidle driver only work in secure mode?
> 
> To my understanding of the hardware, the flow controller can be accessed
> from both worlds. So, testing the mode would neither be sufficient nor
> more logical - it's PSCI which occupies this resource, not automatically
> all secure monitors.

This is correct. The flow controller doesn't check the NS bit.

Cheers,

Peter.