• James kung's avatar
    Prevent pending G1S interrupt become G0 interrupt · acc29852
    James kung authored
    According to Arm GIC spec(IHI0069E, section 4.6.1),
    when GICD_CTLR.DS == 0, Secure Group 1 interrupts
    are treated as Group 0 by a CPU interface if:
    - The PE does not implement EL3.
    - ICC_SRE_EL1(S).SRE == 0
    
    When a cpu enter suspend or deep idle, it might be
    powered off. When the cpu resume, according to
    the GIC spec(IHI0069E, section 9.2.15, 9.2.16 and
    9.2.22) the ICC_SRE_EL1.SRE reset value is 0 (if
    write is allowed) and G0/G1S/G1NS interrupt of the
    GIC cpu interface are all disabled.
    
    If a G1S SPI interrupt occurred and the target cpu
    of the SPI is assigned to a specific cpu which is
    in suspend and is powered off, when the cpu resume
    and start to initial the GIC cpu interface, the
    initial sequence might affect the interrupt group
    type of the pending interrupt on the cpu interface.
    
    Current initial sequence on the cpu interface is:
    1. Enable G0 interrupt
    2. Enable G1S interrupt
    3. Enable ICC_SRE_EL1(S).SRE
    
    It is possible to treat the pending G1S interrupt
    as G0 interrupt on the cpu interface if the G1S
    SPI interrupt occurred between step2 and step3.
    
    To prevent the above situation happend, the initial
    sequence should be changed as follows:
    1. Enable ICC_SRE_EL1(S).SRE
    2. Enable G0 interrupt
    3. Enable G1S interrupt
    
    Change-Id: Ie34f6e0b32eb9a1677ff72571fd4bfdb5cae25b0
    Signed-off-by: default avatarJames Kung <kong1191@gmail.com>
    acc29852
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