• Chris Metcalf's avatar
    arch/tile: fix __ndelay etc to work better · 13371731
    Chris Metcalf authored
    The current implementations of __ndelay and __udelay call a hypervisor
    service to delay, but the hypervisor service isn't actually implemented
    very well, and the consensus is that Linux should handle figuring this
    out natively and not use a hypervisor service.
    
    By converting nanoseconds to cycles, and then spinning until the
    cycle counter reaches the desired cycle, we get several benefits:
    first, we are sensitive to the actual clock speed; second, we use
    less power by issuing a slow SPR read once every six cycles while
    we delay; and third, we properly handle the case of an interrupt by
    exiting at the target time rather than after some number of cycles.
    Signed-off-by: default avatarChris Metcalf <cmetcalf@tilera.com>
    13371731
time.c 6.33 KB