On 2017/1/19 19:59, Marc Zyngier wrote:
> On 19/01/17 11:14, Ding Tianhong wrote:
>> The workaround for hisilicon,161010101 will check the return value of the system counter
>> by different way, in order to distinguish with the fsl-a008585 workaround, introduce
>> a new generic erratum handing mechanism for fsl-a008585 and rename some functions.
>>
>> After discussion with Marc and Will, a consensus decision was made to remove the commandline
>> parameter for enabling fsl,erratum-a008585 erratum.
>>
>> Signed-off-by: Ding Tianhong <dingtianhong@xxxxxxxxxx>
>> ---
>> Documentation/admin-guide/kernel-parameters.txt | 9 --
>> arch/arm64/include/asm/arch_timer.h | 38 +++------
>> drivers/clocksource/Kconfig | 8 ++
>> drivers/clocksource/arm_arch_timer.c | 105 ++++++++++++++----------
>> 4 files changed, 84 insertions(+), 76 deletions(-)
>>
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index 21e2d88..76437ad 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -539,15 +539,6 @@
>> loops can be debugged more effectively on production
>> systems.
>>
>> - clocksource.arm_arch_timer.fsl-a008585=
>> - [ARM64]
>> - Format: <bool>
>> - Enable/disable the workaround of Freescale/NXP
>> - erratum A-008585. This can be useful for KVM
>> - guests, if the guest device tree doesn't show the
>> - erratum. If unspecified, the workaround is
>> - enabled based on the device tree.
>> -
>> clearcpuid=BITNUM [X86]
>> Disable CPUID feature X for the kernel. See
>> arch/x86/include/asm/cpufeatures.h for the valid bit
>> diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
>> index eaa5bbe..b4b3400 100644
>> --- a/arch/arm64/include/asm/arch_timer.h
>> +++ b/arch/arm64/include/asm/arch_timer.h
>> @@ -29,41 +29,29 @@
>>
>> #include <clocksource/arm_arch_timer.h>
>>
>> -#if IS_ENABLED(CONFIG_FSL_ERRATUM_A008585)
>> +#if IS_ENABLED(CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND)
>> extern struct static_key_false arch_timer_read_ool_enabled;
>> -#define needs_fsl_a008585_workaround() \
>> +#define needs_unstable_timer_counter_workaround() \
>> static_branch_unlikely(&arch_timer_read_ool_enabled)
>> #else
>> -#define needs_fsl_a008585_workaround() false
>> +#define needs_unstable_timer_counter_workaround() false
>> #endif
>>
>> -u32 __fsl_a008585_read_cntp_tval_el0(void);
>> -u32 __fsl_a008585_read_cntv_tval_el0(void);
>> -u64 __fsl_a008585_read_cntvct_el0(void);
>>
>> -/*
>> - * The number of retries is an arbitrary value well beyond the highest number
>> - * of iterations the loop has been observed to take.
>> - */
>> -#define __fsl_a008585_read_reg(reg) ({ \
>> - u64 _old, _new; \
>> - int _retries = 200; \
>> - \
>> - do { \
>> - _old = read_sysreg(reg); \
>> - _new = read_sysreg(reg); \
>> - _retries--; \
>> - } while (unlikely(_old != _new) && _retries); \
>> - \
>> - WARN_ON_ONCE(!_retries); \
>> - _new; \
>> -})
>> +struct arch_timer_erratum_workaround {
>> + const char *id; /* Indicate the Erratum ID */
>> + u32 (*read_cntp_tval_el0)(void);
>> + u32 (*read_cntv_tval_el0)(void);
>> + u64 (*read_cntvct_el0)(void);
>> +};
>> +
>> +extern const struct arch_timer_erratum_workaround *timer_unstable_counter_workaround;
>>
>> #define arch_timer_reg_read_stable(reg) \
>> ({ \
>> u64 _val; \
>> - if (needs_fsl_a008585_workaround()) \
>> - _val = __fsl_a008585_read_##reg(); \
>> + if (needs_unstable_timer_counter_workaround()) \
>> + _val = timer_unstable_counter_workaround->read_##reg();\
>> else \
>> _val = read_sysreg(reg); \
>> _val; \
>> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
>> index 4866f7a..04c2b93 100644
>> --- a/drivers/clocksource/Kconfig
>> +++ b/drivers/clocksource/Kconfig
>> @@ -325,10 +325,18 @@ config ARM_ARCH_TIMER_EVTSTREAM
>> This must be disabled for hardware validation purposes to detect any
>> hardware anomalies of missing events.
>>
>> +config ARM_ARCH_TIMER_OOL_WORKAROUND
>> + bool "Workaround for arm arch timer unstable counter"
>
> Please drop the message. We don't want that option to be selectable by a
> user, but only selected if an erratum that depends on it is enabled.
>
OK
Thanks
Ding
>> + depends on FSL_ERRATUM_A008585
>> + help
>> + This option would only be enabled by Freescale/NXP Erratum A-008585
>> + or something else chip has similar erratum.
>> +
>> config FSL_ERRATUM_A008585
>> bool "Workaround for Freescale/NXP Erratum A-008585"
>> default y
>> depends on ARM_ARCH_TIMER && ARM64
>> + select ARM_ARCH_TIMER_OOL_WORKAROUND
>> help
>> This option enables a workaround for Freescale/NXP Erratum
>> A-008585 ("ARM generic timer may contain an erroneous
>
> Thanks,
>
> M.
>
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