linux-kernel - Re: [PATCH v2 1/7] arm64: capabilities: Merge entries for ARM64_WORKAROUND_CLEAN

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Date:   Wed, 5 Dec 2018 17:14:53 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     Will Deacon <will.deacon@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        catalin.marinas@....com, dave.martin@....com, mark.rutland@....com,
        vladimir.murzin@....com, Andre Przywara <andre.przywara@....com>
Subject: Re: [PATCH v2 1/7] arm64: capabilities: Merge entries for
 ARM64_WORKAROUND_CLEAN_CACHE



On 05/12/2018 15:02, Will Deacon wrote:
> On Fri, Nov 30, 2018 at 05:18:00PM +0000, Suzuki K Poulose wrote:
>> We have two entries for ARM64_WORKAROUND_CLEAN_CACHE capability :
>>
>> 1) ARM Errata 826319, 827319, 824069, 819472 on A53 r0p[012]
>> 2) ARM Errata 819472 on A53 r0p[01]
>>
>> Both have the same work around. Merge these entries to avoid
>> duplicate entries for a single capability. Add a new Kconfig
>> entry to control the "capability" entry to make it easier
>> to handle combinations of the CONFIGs.
>>
>> Cc: Will Deacon <will.deacon@....com>
>> Cc: Andre Przywara <andre.przywara@....com>
>> Cc: Mark Rutland <mark.rutland@....com>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
>> ---
>>   arch/arm64/Kconfig               |  7 +++++++
>>   arch/arm64/include/asm/cputype.h |  1 +
>>   arch/arm64/kernel/cpu_errata.c   | 28 ++++++++++++++++------------
>>   3 files changed, 24 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 787d785..ad69e15 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -313,9 +313,13 @@ menu "Kernel Features"
>>   
>>   menu "ARM errata workarounds via the alternatives framework"
>>   
>> +config ARM64_WORKAROUND_CLEAN_CACHE
>> +	def_bool n
>> +
>>   config ARM64_ERRATUM_826319
>>   	bool "Cortex-A53: 826319: System might deadlock if a write cannot complete until read data is accepted"
>>   	default y
>> +	select ARM64_WORKAROUND_CLEAN_CACHE
>>   	help
>>   	  This option adds an alternative code sequence to work around ARM
>>   	  erratum 826319 on Cortex-A53 parts up to r0p2 with an AMBA 4 ACE or
>> @@ -337,6 +341,7 @@ config ARM64_ERRATUM_826319
>>   config ARM64_ERRATUM_827319
>>   	bool "Cortex-A53: 827319: Data cache clean instructions might cause overlapping transactions to the interconnect"
>>   	default y
>> +	select ARM64_WORKAROUND_CLEAN_CACHE
>>   	help
>>   	  This option adds an alternative code sequence to work around ARM
>>   	  erratum 827319 on Cortex-A53 parts up to r0p2 with an AMBA 5 CHI
>> @@ -358,6 +363,7 @@ config ARM64_ERRATUM_827319
>>   config ARM64_ERRATUM_824069
>>   	bool "Cortex-A53: 824069: Cache line might not be marked as clean after a CleanShared snoop"
>>   	default y
>> +	select ARM64_WORKAROUND_CLEAN_CACHE
>>   	help
>>   	  This option adds an alternative code sequence to work around ARM
>>   	  erratum 824069 on Cortex-A53 parts up to r0p2 when it is connected
>> @@ -380,6 +386,7 @@ config ARM64_ERRATUM_824069
>>   config ARM64_ERRATUM_819472
>>   	bool "Cortex-A53: 819472: Store exclusive instructions might cause data corruption"
>>   	default y
>> +	select ARM64_WORKAROUND_CLEAN_CACHE
>>   	help
>>   	  This option adds an alternative code sequence to work around ARM
>>   	  erratum 819472 on Cortex-A53 parts up to r0p1 with an L2 cache
>> diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
>> index 12f93e4d..2e26375 100644
>> --- a/arch/arm64/include/asm/cputype.h
>> +++ b/arch/arm64/include/asm/cputype.h
>> @@ -151,6 +151,7 @@ struct midr_range {
>>   		.rv_max = MIDR_CPU_VAR_REV(v_max, r_max),	\
>>   	}
>>   
>> +#define MIDR_REV_RANGE(m, v, r_min, r_max) MIDR_RANGE(m, v, r_min, v, r_max)
> 
> What's the point of this macro?

That can be used to specify a set of MIDRs which has the same "variant" but a
range of "revisions". This is used for the A53 errata and also for the Cavium
errata in the following patch.

Suzuki