[PATCH] arm-cci: Do not enable CCI-400 PMU by default

[PATCH] arm-cci: Do not enable CCI-400 PMU by default

[Suzuki K. Poulose]

From: "Suzuki K. Poulose" <suzuki.poulose@arm.com>

Do not enable CCI-400 PMU by default and fix the dependency on PERF_EVENTS
than HW_PERF_EVENTS.

Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Cc: arm at vger.kernel.org
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
---
 drivers/bus/Kconfig |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index a1d4af6..62a7ffc 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -13,15 +13,13 @@ config ARM_CCI400_COMMON
 
 config ARM_CCI400_PMU
 	bool "ARM CCI400 PMU support"
-	default y
 	depends on ARM || ARM64
-	depends on HW_PERF_EVENTS
+	depends on PERF_EVENTS
 	select ARM_CCI400_COMMON
 	help
-	  Support for PMU events monitoring on the ARM CCI cache coherent
-	  interconnect.
-
-	  If unsure, say Y
+	  Support for PMU events monitoring on the ARM CCI-400 (cache coherent
+	  interconnect). CCI-400 supports counting events related to the
+	  connected slave/master interfaces.
 
 config ARM_CCI400_PORT_CTRL
 	bool
-- 
1.7.9.5

[PATCH] arm-cci: Do not enable CCI-400 PMU by default

[Russell King - ARM Linux]

On Mon, May 11, 2015 at 01:50:26PM +0100, Suzuki K. Poulose wrote:
>  config ARM_CCI400_PMU
>  	bool "ARM CCI400 PMU support"
> -	default y
>  	depends on ARM || ARM64
> -	depends on HW_PERF_EVENTS
> +	depends on PERF_EVENTS
>  	select ARM_CCI400_COMMON
>  	help
> -	  Support for PMU events monitoring on the ARM CCI cache coherent
> -	  interconnect.
> -
> -	  If unsure, say Y
> +	  Support for PMU events monitoring on the ARM CCI-400 (cache coherent
> +	  interconnect). CCI-400 supports counting events related to the
> +	  connected slave/master interfaces.

This still needs to be better.  How do I know whether it should be enabled
for my platform or not?

Presumably, we can say that CCI-400 does not appear on CPUs older than X,
which means we can add "The CCI-400 may be provided on ARM CPUs X or
later."

I doubt that you'll find CCI-400 on ARMv6 or older ARM architectures for
example.  Maybe then we need "depends on ARM || ARM64" to be tighter?
"depends on (ARM && CPU_V7) || ARM64" ?

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

[PATCH] arm-cci: Do not enable CCI-400 PMU by default

[Suzuki K. Poulose]

On 11/05/15 15:07, Russell King - ARM Linux wrote:
> On Mon, May 11, 2015 at 01:50:26PM +0100, Suzuki K. Poulose wrote:
>>   config ARM_CCI400_PMU
>>   	bool "ARM CCI400 PMU support"
>> -	default y
>>   	depends on ARM || ARM64
>> -	depends on HW_PERF_EVENTS
>> +	depends on PERF_EVENTS
>>   	select ARM_CCI400_COMMON
>>   	help
>> -	  Support for PMU events monitoring on the ARM CCI cache coherent
>> -	  interconnect.
>> -
>> -	  If unsure, say Y
>> +	  Support for PMU events monitoring on the ARM CCI-400 (cache coherent
>> +	  interconnect). CCI-400 supports counting events related to the
>> +	  connected slave/master interfaces.
>
> This still needs to be better.  How do I know whether it should be enabled
> for my platform or not?
>
> Presumably, we can say that CCI-400 does not appear on CPUs older than X,
> which means we can add "The CCI-400 may be provided on ARM CPUs X or
> later."
>
> I doubt that you'll find CCI-400 on ARMv6 or older ARM architectures for
> example.  Maybe then we need "depends on ARM || ARM64" to be tighter?
> "depends on (ARM && CPU_V7) || ARM64" ?
>
Yes, the CCI-400 could be found only on V7 or later (which could include 
32bit only V8) for ARM32.

I can fix that.

Suzuki