Mediatek mailbox controller implement its own data queue rather than using mailbox framework's queue. This series let the framework provide abort function and Mediatek mailbox controller implement the abort-function, so it could use framework's queue.
The reason that Mediatek mailbox controller has to implement its own queue: One client of Mediatek mailbox controller is display driver. When a cursor is moving, display continuously update the register related to the cursor. Display hardware has a limitation that register should be updated in the vblank period which is a small interval. In tradition, display hardware would trigger an interrupt when vblank start, and driver could update register in this irq handler. But the interrupt handler has the risk that it could be delayed by some reason so the handler may be postponed out of this vblank interval. In order to reduce the risk, display driver use GCE hardware to write register. If a cursor move 3 times before vblank, display driver would send 3 messages sequentially to mailbox controller. If the controller use framework's queue, controller just receive the first message and the others is queued in framework. The first message could be executed exactly in vblank interval but the other messages are sent to controller when controller notify framework tx_done in interrupt handler. The interrupt may be postponed by some reason this is what we worried. So Mediatek mailbox controller has to implement its own queue to make sure that all message execute in vblank interval. The reason that abort-function could let Mediatek mailbox controller use framework's queue: The primary concept is to let display driver send at most one message to mailbox controller. When it need to send the second message before the first message is done, it should abort the first message and then send the second message which should merge the first message. For other client driver, it could still send multiple messages into framework's queue. CK Hu (3): mailbox: Add ability for clients to abort data in channel mailbox: mediatek: Implement abort_data function. mailbox: mediatek: Remove busylist drivers/mailbox/mailbox.c | 23 +++ drivers/mailbox/mtk-cmdq-mailbox.c | 281 +++++++---------------------- include/linux/mailbox_client.h | 1 + include/linux/mailbox_controller.h | 4 + 4 files changed, 90 insertions(+), 219 deletions(-) -- 2.18.0