2023-08-02 06:53:51

by Anshuman Khandual

Subject: [PATCH] coresight: trbe: Directly use ID_AA64DFR0_EL1_TraceBuffer_IMP

is_trbe_available() checks for the TRBE support via extracting TraceBuffer
field value from ID_AA64DFR0_EL1, and ensures that it is implemented. This
replaces the open encoding '0b0001' with 'ID_AA64DFR0_EL1_TraceBuffer_IMP'
which is now available via sysreg tools. Functional change is not intended.

Cc: Suzuki K Poulose <[email protected]>
Cc: Mike Leach <[email protected]>
Cc: James Clark <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Anshuman Khandual <[email protected]>
---
drivers/hwtracing/coresight/coresight-trbe.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.h b/drivers/hwtracing/coresight/coresight-trbe.h
index 94e67009848a..ebb9108d8e24 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.h
+++ b/drivers/hwtracing/coresight/coresight-trbe.h
@@ -24,7 +24,7 @@ static inline bool is_trbe_available(void)
unsigned int trbe = cpuid_feature_extract_unsigned_field(aa64dfr0,
ID_AA64DFR0_EL1_TraceBuffer_SHIFT);

- return trbe >= 0b0001;
+ return trbe >= ID_AA64DFR0_EL1_TraceBuffer_IMP;
}

static inline bool is_trbe_enabled(void)
--
2.25.1

2023-08-02 09:58:32

by James Clark

Subject: Re: [PATCH] coresight: trbe: Directly use ID_AA64DFR0_EL1_TraceBuffer_IMP

On 02/08/2023 07:36, Anshuman Khandual wrote:
> is_trbe_available() checks for the TRBE support via extracting TraceBuffer
> field value from ID_AA64DFR0_EL1, and ensures that it is implemented. This
> replaces the open encoding '0b0001' with 'ID_AA64DFR0_EL1_TraceBuffer_IMP'
> which is now available via sysreg tools. Functional change is not intended.
>
> Cc: Suzuki K Poulose <[email protected]>
> Cc: Mike Leach <[email protected]>
> Cc: James Clark <[email protected]>
> Cc: Leo Yan <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Anshuman Khandual <[email protected]>
> ---
> drivers/hwtracing/coresight/coresight-trbe.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-trbe.h b/drivers/hwtracing/coresight/coresight-trbe.h
> index 94e67009848a..ebb9108d8e24 100644
> --- a/drivers/hwtracing/coresight/coresight-trbe.h
> +++ b/drivers/hwtracing/coresight/coresight-trbe.h
> @@ -24,7 +24,7 @@ static inline bool is_trbe_available(void)
> unsigned int trbe = cpuid_feature_extract_unsigned_field(aa64dfr0,
> ID_AA64DFR0_EL1_TraceBuffer_SHIFT);
>
> - return trbe >= 0b0001;
> + return trbe >= ID_AA64DFR0_EL1_TraceBuffer_IMP;
> }
>
> static inline bool is_trbe_enabled(void)

Reviewed-by: James Clark <[email protected]>

Kind of unrelated to this change, but it seems like a lot of feature
checks like this avoid using any value altogether when it's just 0 or 1.
For example the same check for TRBE in kvm:

/* Check if we have TRBE implemented and available at the host */
if (cpuid_feature_extract_unsigned_field(dfr0,
ID_AA64DFR0_EL1_TraceBuffer_SHIFT) &&
...

2023-08-02 13:21:41

by Suzuki K Poulose

Subject: Re: [PATCH] coresight: trbe: Directly use ID_AA64DFR0_EL1_TraceBuffer_IMP

On Wed, 2 Aug 2023 12:06:58 +0530, Anshuman Khandual wrote:
> is_trbe_available() checks for the TRBE support via extracting TraceBuffer
> field value from ID_AA64DFR0_EL1, and ensures that it is implemented. This
> replaces the open encoding '0b0001' with 'ID_AA64DFR0_EL1_TraceBuffer_IMP'
> which is now available via sysreg tools. Functional change is not intended.
>
>

Applied, thanks!

[1/1] coresight: trbe: Directly use ID_AA64DFR0_EL1_TraceBuffer_IMP
https://git.kernel.org/coresight/c/c00701125cf379f8ce9a4c98cb3cbf9edc3a5672

Best regards,
--
Suzuki K Poulose <[email protected]>