• Benjamin Tissoires's avatar
    i2c: use an IRQ to report Host Notify events, not alert · 4d5538f5
    Benjamin Tissoires authored
    The current SMBus Host Notify implementation relies on .alert() to
    relay its notifications. However, the use cases where SMBus Host
    Notify is needed currently is to signal data ready on touchpads.
    This is closer to an IRQ than a custom API through .alert().
    Given that the 2 touchpad manufacturers (Synaptics and Elan) that
    use SMBus Host Notify don't put any data in the SMBus payload, the
    concept actually matches one to one.
    Benefits are multiple:
    - simpler code and API: the client will just have an IRQ, and
      nothing needs to be added in the adapter beside internally
      enabling it.
    - no more specific workqueue, the threading is handled by IRQ core
      directly (when required)
    - no more races when removing the device (the drivers are already
      required to disable irq on remove)
    - simpler handling for drivers: use plain regular IRQs
    - no more dependency on i2c-smbus for i2c-i801 (and any other adapter)
    - the IRQ domain is created automatically when the adapter exports
      the Host Notify capability
    - the IRQ are assign only if ACPI, OF and the caller did not assign
      one already
    - the domain is automatically destroyed on remove
    - fewer lines of code (minus 20, yeah!)
    Signed-off-by: Benjamin Tissoires's avatarBenjamin Tissoires <benjamin.tissoires@redhat.com>
    Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
smbus-protocol 9.42 KB