• Maarten Lankhorst's avatar
    seqno-fence: Hardware dma-buf implementation of fencing (v6) · 606b23ad
    Maarten Lankhorst authored
    This type of fence can be used with hardware synchronization for simple
    hardware that can block execution until the condition
    (dma_buf[offset] - value) >= 0 has been met when WAIT_GEQUAL is used,
    or (dma_buf[offset] != 0) has been met when WAIT_NONZERO is set.
    A software fallback still has to be provided in case the fence is used
    with a device that doesn't support this mechanism. It is useful to expose
    this for graphics cards that have an op to support this.
    Some cards like i915 can export those, but don't have an option to wait,
    so they need the software fallback.
    I extended the original patch by Rob Clark.
    v1: Original
    v2: Renamed from bikeshed to seqno, moved into dma-fence.c since
        not much was left of the file. Lots of documentation added.
    v3: Use fence_ops instead of custom callbacks. Moved to own file
        to avoid circular dependency between dma-buf.h and fence.h
    v4: Add spinlock pointer to seqno_fence_init
    v5: Add condition member to allow wait for != 0.
        Fix small style errors pointed out by checkpatch.
    v6: Move to a separate file. Fix up api changes in fences.
    Signed-off-by: default avatarMaarten Lankhorst <maarten.lankhorst@canonical.com>
    Acked-by: default avatarSumit Semwal <sumit.semwal@linaro.org>
    Acked-by: default avatarDaniel Vetter <daniel@ffwll.ch>
    Reviewed-by: Rob Clark <robdclark@gmail.com> #v4
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
device-drivers.tmpl 15.2 KB