Re: [PATCH, RFC 2/8] ARM: twd: register clock event for 1 core SMP
On Tuesday 19 February 2013 05:44 PM, Felipe Balbi wrote: On Tue, Feb 19, 2013 at 03:44:14PM +0530, Santosh Shilimkar wrote: On Monday 18 February 2013 05:07 PM, Afzal Mohammed wrote: Register percpu local timer for scheduler tick in the case of one core SMP configuration. In other cases - secondary cpu's as well as boot cpu's having more than one core, this is being registered as per existing boot flow, with a difference that they happens after delay calibration. Registering the clock for tick in case of one core should be done before Kernel calibrates delay (this is required to boot, unless local timer is the only one registered for tick). Registering twd local timer at init_time (which platforms are doing now) helps achieve that with the proposed change. This helps in an almost booting Kernel (minimal) by only relying on ARM parts for an A9 one core SMP. Signed-off-by: Afzal Mohammed --- As mentioned in cover-letter, I don't think we have good reasoning to make TWD to work with UP configuration. Even you fix the timer code, there are more cascaded dependencies which is not worth the effort. if CONFIG_SMP_ON_UP is enabled, smp_twd.c can still be compiled, right ? Yep though just from deps pesrpective TWD is made available for ARM SMP machines as below config HAVE_ARM_TWD bool depends on SMP Regards, Santosh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH, RFC 2/8] ARM: twd: register clock event for 1 core SMP
On Tue, Feb 19, 2013 at 03:44:14PM +0530, Santosh Shilimkar wrote: > On Monday 18 February 2013 05:07 PM, Afzal Mohammed wrote: > >Register percpu local timer for scheduler tick in the case of one core > >SMP configuration. In other cases - secondary cpu's as well as boot > >cpu's having more than one core, this is being registered as per > >existing boot flow, with a difference that they happens after delay > >calibration. Registering the clock for tick in case of one core should > >be done before Kernel calibrates delay (this is required to boot, > >unless local timer is the only one registered for tick). Registering > >twd local timer at init_time (which platforms are doing now) helps > >achieve that with the proposed change. > > > >This helps in an almost booting Kernel (minimal) by only relying on > >ARM parts for an A9 one core SMP. > > > >Signed-off-by: Afzal Mohammed > >--- > As mentioned in cover-letter, I don't think we have good > reasoning to make TWD to work with UP configuration. Even > you fix the timer code, there are more cascaded dependencies > which is not worth the effort. if CONFIG_SMP_ON_UP is enabled, smp_twd.c can still be compiled, right ? -- balbi signature.asc Description: Digital signature
Re: [PATCH, RFC 2/8] ARM: twd: register clock event for 1 core SMP
On Monday 18 February 2013 05:07 PM, Afzal Mohammed wrote: Register percpu local timer for scheduler tick in the case of one core SMP configuration. In other cases - secondary cpu's as well as boot cpu's having more than one core, this is being registered as per existing boot flow, with a difference that they happens after delay calibration. Registering the clock for tick in case of one core should be done before Kernel calibrates delay (this is required to boot, unless local timer is the only one registered for tick). Registering twd local timer at init_time (which platforms are doing now) helps achieve that with the proposed change. This helps in an almost booting Kernel (minimal) by only relying on ARM parts for an A9 one core SMP. Signed-off-by: Afzal Mohammed --- As mentioned in cover-letter, I don't think we have good reasoning to make TWD to work with UP configuration. Even you fix the timer code, there are more cascaded dependencies which is not worth the effort. Regards, Samtosh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH, RFC 2/8] ARM: twd: register clock event for 1 core SMP
On Monday 18 February 2013 05:07 PM, Afzal Mohammed wrote: Register percpu local timer for scheduler tick in the case of one core SMP configuration. In other cases - secondary cpu's as well as boot cpu's having more than one core, this is being registered as per existing boot flow, with a difference that they happens after delay calibration. Registering the clock for tick in case of one core should be done before Kernel calibrates delay (this is required to boot, unless local timer is the only one registered for tick). Registering twd local timer at init_time (which platforms are doing now) helps achieve that with the proposed change. This helps in an almost booting Kernel (minimal) by only relying on ARM parts for an A9 one core SMP. Signed-off-by: Afzal Mohammed af...@ti.com --- As mentioned in cover-letter, I don't think we have good reasoning to make TWD to work with UP configuration. Even you fix the timer code, there are more cascaded dependencies which is not worth the effort. Regards, Samtosh -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH, RFC 2/8] ARM: twd: register clock event for 1 core SMP
On Tue, Feb 19, 2013 at 03:44:14PM +0530, Santosh Shilimkar wrote: On Monday 18 February 2013 05:07 PM, Afzal Mohammed wrote: Register percpu local timer for scheduler tick in the case of one core SMP configuration. In other cases - secondary cpu's as well as boot cpu's having more than one core, this is being registered as per existing boot flow, with a difference that they happens after delay calibration. Registering the clock for tick in case of one core should be done before Kernel calibrates delay (this is required to boot, unless local timer is the only one registered for tick). Registering twd local timer at init_time (which platforms are doing now) helps achieve that with the proposed change. This helps in an almost booting Kernel (minimal) by only relying on ARM parts for an A9 one core SMP. Signed-off-by: Afzal Mohammed af...@ti.com --- As mentioned in cover-letter, I don't think we have good reasoning to make TWD to work with UP configuration. Even you fix the timer code, there are more cascaded dependencies which is not worth the effort. if CONFIG_SMP_ON_UP is enabled, smp_twd.c can still be compiled, right ? -- balbi signature.asc Description: Digital signature
Re: [PATCH, RFC 2/8] ARM: twd: register clock event for 1 core SMP
On Tuesday 19 February 2013 05:44 PM, Felipe Balbi wrote: On Tue, Feb 19, 2013 at 03:44:14PM +0530, Santosh Shilimkar wrote: On Monday 18 February 2013 05:07 PM, Afzal Mohammed wrote: Register percpu local timer for scheduler tick in the case of one core SMP configuration. In other cases - secondary cpu's as well as boot cpu's having more than one core, this is being registered as per existing boot flow, with a difference that they happens after delay calibration. Registering the clock for tick in case of one core should be done before Kernel calibrates delay (this is required to boot, unless local timer is the only one registered for tick). Registering twd local timer at init_time (which platforms are doing now) helps achieve that with the proposed change. This helps in an almost booting Kernel (minimal) by only relying on ARM parts for an A9 one core SMP. Signed-off-by: Afzal Mohammed af...@ti.com --- As mentioned in cover-letter, I don't think we have good reasoning to make TWD to work with UP configuration. Even you fix the timer code, there are more cascaded dependencies which is not worth the effort. if CONFIG_SMP_ON_UP is enabled, smp_twd.c can still be compiled, right ? Yep though just from deps pesrpective TWD is made available for ARM SMP machines as below config HAVE_ARM_TWD bool depends on SMP Regards, Santosh -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH, RFC 2/8] ARM: twd: register clock event for 1 core SMP
Register percpu local timer for scheduler tick in the case of one core SMP configuration. In other cases - secondary cpu's as well as boot cpu's having more than one core, this is being registered as per existing boot flow, with a difference that they happens after delay calibration. Registering the clock for tick in case of one core should be done before Kernel calibrates delay (this is required to boot, unless local timer is the only one registered for tick). Registering twd local timer at init_time (which platforms are doing now) helps achieve that with the proposed change. This helps in an almost booting Kernel (minimal) by only relying on ARM parts for an A9 one core SMP. Signed-off-by: Afzal Mohammed --- arch/arm/kernel/smp_twd.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c index 616268c..118f4f2 100644 --- a/arch/arm/kernel/smp_twd.c +++ b/arch/arm/kernel/smp_twd.c @@ -335,6 +335,9 @@ static int __init twd_local_timer_common_register(struct device_node *np) twd_get_clock(np); + if (num_possible_cpus() == 1) + twd_timer_setup(evt); + return 0; out_irq: -- 1.7.12 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH, RFC 2/8] ARM: twd: register clock event for 1 core SMP
Register percpu local timer for scheduler tick in the case of one core SMP configuration. In other cases - secondary cpu's as well as boot cpu's having more than one core, this is being registered as per existing boot flow, with a difference that they happens after delay calibration. Registering the clock for tick in case of one core should be done before Kernel calibrates delay (this is required to boot, unless local timer is the only one registered for tick). Registering twd local timer at init_time (which platforms are doing now) helps achieve that with the proposed change. This helps in an almost booting Kernel (minimal) by only relying on ARM parts for an A9 one core SMP. Signed-off-by: Afzal Mohammed af...@ti.com --- arch/arm/kernel/smp_twd.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c index 616268c..118f4f2 100644 --- a/arch/arm/kernel/smp_twd.c +++ b/arch/arm/kernel/smp_twd.c @@ -335,6 +335,9 @@ static int __init twd_local_timer_common_register(struct device_node *np) twd_get_clock(np); + if (num_possible_cpus() == 1) + twd_timer_setup(evt); + return 0; out_irq: -- 1.7.12 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
