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* [PATCH V4] ARM: mach-shmobile: Don't init CNTVOFF/counter if PSCI is available
@ 2019-05-14 16:06 Oleksandr Tyshchenko
  2019-05-14 16:13 ` Julien Grall
  0 siblings, 1 reply; 3+ messages in thread
From: Oleksandr Tyshchenko @ 2019-05-14 16:06 UTC (permalink / raw)
  To: linux-renesas-soc, linux-kernel
  Cc: julien.grall, horms, magnus.damm, linux, geert, Oleksandr Tyshchenko

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

If PSCI is available then most likely we are running on PSCI-enabled
U-Boot which, we assume, has already taken care of resetting CNTVOFF
and updating counter module before switching to non-secure mode
and we don't need to.

As the psci_smp_available() helper always returns false if CONFIG_SMP
is disabled, it can't be used safely as an indicator of PSCI usage.
For that reason, we check for the mandatory PSCI operation to be
available.

Please note, an extra check to prevent secure_cntvoff_init() from
being called for secondary CPUs in headsmp-apmu.S is not needed,
as SMP code for APMU based system is not executed if PSCI is in use.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
CC: Julien Grall <julien.grall@arm.com>

---
   You can find previous discussions here:
   [v1]  https://lkml.org/lkml/2019/4/17/810
   [v2]  https://lkml.org/lkml/2019/5/3/338
   [v3]  https://lkml.org/lkml/2019/5/10/415
   [RFC] https://lkml.org/lkml/2019/5/10/473

   Changes in v2:
      - Clarify patch subject/description
      - Don't use CONFIG_ARM_PSCI option, check whether the PSCI is available,
        by using psci_smp_available()
      - Check whether we are running on top of Xen, by using xen_domain()

   Changes in v3:
      - Don't check for the presence of Xen

   Changes in v4:
      - Don't use psci_smp_available() helper, check for psci_ops.cpu_on
        directly
      - Skip updating counter module if PSCI is available
---
 arch/arm/mach-shmobile/setup-rcar-gen2.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/arm/mach-shmobile/setup-rcar-gen2.c b/arch/arm/mach-shmobile/setup-rcar-gen2.c
index eea60b2..64e3abd 100644
--- a/arch/arm/mach-shmobile/setup-rcar-gen2.c
+++ b/arch/arm/mach-shmobile/setup-rcar-gen2.c
@@ -17,6 +17,7 @@
 #include <linux/of.h>
 #include <linux/of_fdt.h>
 #include <linux/of_platform.h>
+#include <linux/psci.h>
 #include <asm/mach/arch.h>
 #include <asm/secure_cntvoff.h>
 #include "common.h"
@@ -63,6 +64,15 @@ void __init rcar_gen2_timer_init(void)
 	void __iomem *base;
 	u32 freq;
 
+	/*
+	 * If PSCI is available then most likely we are running on PSCI-enabled
+	 * U-Boot which, we assume, has already taken care of resetting CNTVOFF
+	 * and updating counter module before switching to non-secure mode
+	 * and we don't need to.
+	 */
+	if (psci_ops.cpu_on)
+		goto skip_update;
+
 	secure_cntvoff_init();
 
 	if (of_machine_is_compatible("renesas,r8a7745") ||
@@ -102,6 +112,7 @@ void __init rcar_gen2_timer_init(void)
 
 	iounmap(base);
 
+skip_update:
 	of_clk_init(NULL);
 	timer_probe();
 }
-- 
2.7.4


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH V4] ARM: mach-shmobile: Don't init CNTVOFF/counter if PSCI is available
  2019-05-14 16:06 [PATCH V4] ARM: mach-shmobile: Don't init CNTVOFF/counter if PSCI is available Oleksandr Tyshchenko
@ 2019-05-14 16:13 ` Julien Grall
  2019-05-14 16:51   ` Oleksandr
  0 siblings, 1 reply; 3+ messages in thread
From: Julien Grall @ 2019-05-14 16:13 UTC (permalink / raw)
  To: Oleksandr Tyshchenko, linux-renesas-soc, linux-kernel
  Cc: horms, magnus.damm, linux, geert, Oleksandr Tyshchenko

Hi,

On 14/05/2019 17:06, Oleksandr Tyshchenko wrote:
> diff --git a/arch/arm/mach-shmobile/setup-rcar-gen2.c b/arch/arm/mach-shmobile/setup-rcar-gen2.c
> index eea60b2..64e3abd 100644
> --- a/arch/arm/mach-shmobile/setup-rcar-gen2.c
> +++ b/arch/arm/mach-shmobile/setup-rcar-gen2.c
> @@ -17,6 +17,7 @@
>   #include <linux/of.h>
>   #include <linux/of_fdt.h>
>   #include <linux/of_platform.h>
> +#include <linux/psci.h>
>   #include <asm/mach/arch.h>
>   #include <asm/secure_cntvoff.h>
>   #include "common.h"
> @@ -63,6 +64,15 @@ void __init rcar_gen2_timer_init(void)
>   	void __iomem *base;
>   	u32 freq;
>   
> +	/*
> +	 * If PSCI is available then most likely we are running on PSCI-enabled
> +	 * U-Boot which, we assume, has already taken care of resetting CNTVOFF
> +	 * and updating counter module before switching to non-secure mode
> +	 * and we don't need to.
> +	 */
> +	if (psci_ops.cpu_on) > +		goto skip_update;
Are you sure this is working when ARM_PSCI_FW is not selected? Is it possible to 
have a .config for RCAR without ARM_PSCI_FW?

Cheers,

-- 
Julien Grall

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH V4] ARM: mach-shmobile: Don't init CNTVOFF/counter if PSCI is available
  2019-05-14 16:13 ` Julien Grall
@ 2019-05-14 16:51   ` Oleksandr
  0 siblings, 0 replies; 3+ messages in thread
From: Oleksandr @ 2019-05-14 16:51 UTC (permalink / raw)
  To: Julien Grall, linux-renesas-soc, linux-kernel
  Cc: horms, magnus.damm, linux, geert, Oleksandr Tyshchenko


On 14.05.19 19:13, Julien Grall wrote:
> Hi,

Hi Julien


>
> On 14/05/2019 17:06, Oleksandr Tyshchenko wrote:
>> diff --git a/arch/arm/mach-shmobile/setup-rcar-gen2.c 
>> b/arch/arm/mach-shmobile/setup-rcar-gen2.c
>> index eea60b2..64e3abd 100644
>> --- a/arch/arm/mach-shmobile/setup-rcar-gen2.c
>> +++ b/arch/arm/mach-shmobile/setup-rcar-gen2.c
>> @@ -17,6 +17,7 @@
>>   #include <linux/of.h>
>>   #include <linux/of_fdt.h>
>>   #include <linux/of_platform.h>
>> +#include <linux/psci.h>
>>   #include <asm/mach/arch.h>
>>   #include <asm/secure_cntvoff.h>
>>   #include "common.h"
>> @@ -63,6 +64,15 @@ void __init rcar_gen2_timer_init(void)
>>       void __iomem *base;
>>       u32 freq;
>>   +    /*
>> +     * If PSCI is available then most likely we are running on 
>> PSCI-enabled
>> +     * U-Boot which, we assume, has already taken care of resetting 
>> CNTVOFF
>> +     * and updating counter module before switching to non-secure mode
>> +     * and we don't need to.
>> +     */
>> +    if (psci_ops.cpu_on) > +        goto skip_update;
> Are you sure this is working when ARM_PSCI_FW is not selected? Is it 
> possible to have a .config for RCAR without ARM_PSCI_FW?

Oh, my fault. Mainline shmobile_defconfig has PSCI stuff disabled.

I should have checked for the PSCI operation to be available only if 
CONFIG_ARM_PSCI_FW is defined.

Thank you for pointing this out.


>
> Cheers,
>
-- 
Regards,

Oleksandr Tyshchenko


^ permalink raw reply	[flat|nested] 3+ messages in thread

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2019-05-14 16:06 [PATCH V4] ARM: mach-shmobile: Don't init CNTVOFF/counter if PSCI is available Oleksandr Tyshchenko
2019-05-14 16:13 ` Julien Grall
2019-05-14 16:51   ` Oleksandr

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