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Re: [PATCH v2 06/18] arm64: arch_timer: Add infrastructure for multiple erratum detection methods

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On 22/03/17 15:41, Daniel Lezcano wrote:
> On Mon, Mar 20, 2017 at 05:48:17PM +0000, Marc Zyngier wrote:
>> We're currently stuck with DT when it comes to handling errata, which
>> is pretty restrictive. In order to make things more flexible, let's
>> introduce an infrastructure that could support alternative discovery
>> methods. No change in functionality.
>>
>> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>> ---
>>  arch/arm64/include/asm/arch_timer.h  |  7 +++-
>>  drivers/clocksource/arm_arch_timer.c | 80 +++++++++++++++++++++++++++++++-----
>>  2 files changed, 75 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
>> index b4b34004a21e..5cd964e90d11 100644
>> --- a/arch/arm64/include/asm/arch_timer.h
>> +++ b/arch/arm64/include/asm/arch_timer.h
>> @@ -37,9 +37,14 @@ extern struct static_key_false arch_timer_read_ool_enabled;
>>  #define needs_unstable_timer_counter_workaround()  false
>>  #endif
>>  
>> +enum arch_timer_erratum_match_type {
>> +	ate_match_dt,
>> +};
>>  
>>  struct arch_timer_erratum_workaround {
>> -	const char *id;		/* Indicate the Erratum ID */
>> +	enum arch_timer_erratum_match_type match_type;
> 
> Putting the match_fn instead will be much more simpler and the code won't
> have to deal with ate_match_type, no ?

I'm not sure about the "much simpler" aspect. Each function is not
necessarily standalone (see patches 8 and 13 for example, dealing with
CPU-local defects). We

> 
> [ ... ]
> 
>> +static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type type,
>> +					    void *arg)
>> +{
>> +	const struct arch_timer_erratum_workaround *wa;
>> +	ate_match_fn_t match_fn = NULL;
>> +
>> +	if (static_branch_unlikely(&arch_timer_read_ool_enabled))
>> +		return;
>> +
> 
> Why is this check necessary ?

We don't allow cumulative workarounds at this stage. This restriction
gets lifted (to some extent) later in the series.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

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[PATCH v2 00/18] clocksource/arch_timer: Errata workaround infrastructure rework Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 18:50 +0100
  [PATCH v2 01/18] arm64: Allow checking of a CPU-local erratum Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 18:50 +0100
    Re: [PATCH v2 01/18] arm64: Allow checking of a CPU-local erratum Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-03-22 10:30 +0100
  [PATCH v2 11/18] arm64: arch_timer: Rework the set_next_event workarounds Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:00 +0100
  [PATCH v2 08/18] arm64: arch_timer: Add erratum handler for CPU-specific capability Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:00 +0100
  [PATCH v2 05/18] arm64: cpu_errata: Add capability to advertise Cortex-A73 erratum 858921 Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:00 +0100
    Re: [PATCH v2 05/18] arm64: cpu_errata: Add capability to advertise  Cortex-A73 erratum 858921 Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-03-22 16:10 +0100
  [PATCH v2 09/18] arm64: arch_timer: Move arch_timer_reg_read/write around Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:00 +0100
    Re: [PATCH v2 09/18] arm64: arch_timer: Move  arch_timer_reg_read/write around Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-03-22 17:00 +0100
  [PATCH v2 07/18] arm64: arch_timer: Add erratum handler for globally defined capability Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:00 +0100
  [PATCH v2 06/18] arm64: arch_timer: Add infrastructure for multiple erratum detection methods Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:40 +0100
    Re: [PATCH v2 06/18] arm64: arch_timer: Add infrastructure for  multiple erratum detection methods Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-03-22 16:50 +0100
      Re: [PATCH v2 06/18] arm64: arch_timer: Add infrastructure for  multiple erratum detection methods Marc Zyngier <marc.zyngier@arm.com> - 2017-03-22 17:00 +0100
      Re: [PATCH v2 06/18] arm64: arch_timer: Add infrastructure for  multiple erratum detection methods Marc Zyngier <marc.zyngier@arm.com> - 2017-03-22 17:00 +0100
        Re: [PATCH v2 06/18] arm64: arch_timer: Add infrastructure for  multiple erratum detection methods Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-03-22 18:10 +0100
        Re: [PATCH v2 06/18] arm64: arch_timer: Add infrastructure for  multiple erratum detection methods Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-03-23 18:40 +0100
          Re: [PATCH v2 06/18] arm64: arch_timer: Add infrastructure for  multiple erratum detection methods Marc Zyngier <marc.zyngier@arm.com> - 2017-03-24 15:00 +0100
            Re: [PATCH v2 06/18] arm64: arch_timer: Add infrastructure for  multiple erratum detection methods Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-03-27 10:00 +0200
    Re: [PATCH v2 06/18] arm64: arch_timer: Add infrastructure for  multiple erratum detection methods dann frazier <dann.frazier@canonical.com> - 2017-03-24 18:50 +0100
      Re: [PATCH v2 06/18] arm64: arch_timer: Add infrastructure for  multiple erratum detection methods Marc Zyngier <marc.zyngier@arm.com> - 2017-03-24 19:20 +0100
  [PATCH v2 15/18] arm64: arch_timer: Enable CNTVCT_EL0 trap if workaround is enabled Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:40 +0100
  [PATCH v2 16/18] arm64: arch_timer: Workaround for Cortex-A73 erratum 858921 Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:40 +0100
  [PATCH v2 13/18] arm64: arch_timer: Allows a CPU-specific erratum to only affect a subset of CPUs Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:40 +0100
  [PATCH v2 04/18] arm64: cpu_errata: Allow an erratum to be match for all revisions of a core Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:40 +0100
    Re: [PATCH v2 04/18] arm64: cpu_errata: Allow an erratum to be match  for all revisions of a core Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-03-22 16:10 +0100
  [PATCH v2 18/18] arm64: arch_timer: Add HISILICON_ERRATUM_161010101 ACPI matching data Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:40 +0100
  [PATCH v2 02/18] arm64: Add CNTVCT_EL0 trap handler Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:40 +0100
  [PATCH v2 03/18] arm64: Define Cortex-A73 MIDR Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:40 +0100
  [PATCH v2 17/18] arm64: arch_timer: Allow erratum matching with ACPI OEM information Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:40 +0100
  [PATCH v2 10/18] arm64: arch_timer: Get rid of erratum_workaround_set_sne Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:50 +0100
  [PATCH v2 12/18] arm64: arch_timer: Make workaround methods optional Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:50 +0100
  [PATCH v2 14/18] arm64: arch_timer: Move clocksource_counter and co around Marc Zyngier <marc.zyngier@arm.com> - 2017-03-20 19:50 +0100
  Re: [PATCH v2 00/18] clocksource/arch_timer: Errata workaround  infrastructure rework Ding Tianhong <dingtianhong@huawei.com> - 2017-03-22 15:00 +0100

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