tree 2955d4b4241a56017f6f64be5caad5eb0e6cdfb4
parent 1bbe51d0b5bef615692afe6ccc24259c1b2208e4
author Peng Qi <peng.qi@mediatek.com> 1497866467 +0800
committer Ting Zheng <ting.zheng@mediatek.com> 1498851131 -0700

BT HAL H4 write flow

If to send type and data separately for one HCI packet,
it will cause two system call context switch to kernel space,
which will introduce software overhead on data path.
Plus, if vendor does not use pure UART interface, it causes different
data behavior on BUS and may not adapt to all vendors as legacy HAL did.
Considering backward-compatibility, to use writev to send
type and data together once as legacy BT HAL did.

Test: H4 UTTest, BT VTS test, Bluetooth on/off
Change-Id: I2d93085fe0c01b48d0e3729a3fa85b5b27335b2c