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    ARM: 7773/1: PJ4B: Add support for errata 4742 · 3e0a07f8
    Gregory CLEMENT 提交于
    This commit fixes the regression on Armada 370 (the kernal hang during
    boot) introduced by the commit: "ARM: 7691/1: mm: kill unused
    TLB_CAN_READ_FROM_L1_CACHE and use ALT_SMP instead".
    
    When coming out of either a Wait for Interrupt (WFI) or a Wait for
    Event (WFE) IDLE states, a specific timing sensitivity exists between
    the retiring WFI/WFE instructions and the newly issued subsequent
    instructions. This sensitivity can result in a CPU hang scenario.  The
    workaround is to insert either a Data Synchronization Barrier (DSB) or
    Data Memory Barrier (DMB) command immediately after the WFI/WFE
    instruction.
    
    This commit was based on the work of Lior Amsalem, but heavily
    modified to apply the errata fix dynamically according to the
    processor type thanks to the suggestions of Russell King and Nicolas
    Pitre.
    Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
    Reviewed-by: NWill Deacon <will.deacon@arm.com>
    Acked-by: NNicolas Pitre <nico@linaro.org>
    Tested-by: NWilly Tarreau <w@1wt.eu>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
    3e0a07f8
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