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    Subject[PATCH v2] arm: remove unused code in delay.S
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    Date
    Document #if 0 code block in delay.S and make it selectable for compile.

    Signed-off-by: Steve Chen <schen@mvista.com>

    ---
    arch/arm/Kconfig | 14 ++++++++++++++
    arch/arm/lib/delay.S | 2 +-
    2 files changed, 15 insertions(+), 1 deletions(-)
    diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
    index aef63c8..ed8bf14 100644
    --- a/arch/arm/Kconfig
    +++ b/arch/arm/Kconfig
    @@ -813,6 +813,20 @@ config ARM_ERRATA_460075
    ACTLR register. Note that setting specific bits in the ACTLR
    register
    may not be available in non-secure mode.

    +config OLD_CPU_DELAY
    + depends on CPU_32v3 || CPU_32v4 || CPU_32v4T
    + bool "Different delay() code for some older CPUs"
    + def_bool n
    + help
    + Enable this if observing longer than expected delays. This code
    + improves delay accuracy for some CPUs. However, it can also cause
    + delay duration to be too short for others which leads to stability
    + issues.
    +
    + In other words, do not enable unless you can guarantee that the
    + processor (or ALL of the processors if building a generic kernel)
    + delays for at least the time requested after enabling.
    +
    endmenu

    source "arch/arm/common/Kconfig"
    diff --git a/arch/arm/lib/delay.S b/arch/arm/lib/delay.S
    index 8d6a876..67e679b 100644
    --- a/arch/arm/lib/delay.S
    +++ b/arch/arm/lib/delay.S
    @@ -42,7 +42,7 @@ ENTRY(__const_udelay) @ 0 <= r0 <= 0x7fffff06
    @ Delay routine
    ENTRY(__delay)
    subs r0, r0, #1
    -#if 0
    +#ifdef CONFIG_OLD_CPU_DELAY
    movls pc, lr
    subs r0, r0, #1
    movls pc, lr



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