From 92afd74a15d15b0ad6eb619a8ad3a864a4f6e71c Mon Sep 17 00:00:00 2001 From: Peng Qi Date: Mon, 19 Jun 2017 18:01:07 +0800 Subject: 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 --- bluetooth/1.0/default/h4_protocol.cc | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) (limited to 'bluetooth') diff --git a/bluetooth/1.0/default/h4_protocol.cc b/bluetooth/1.0/default/h4_protocol.cc index 8f24b5eeac..2df2b3b914 100644 --- a/bluetooth/1.0/default/h4_protocol.cc +++ b/bluetooth/1.0/default/h4_protocol.cc @@ -18,8 +18,10 @@ #define LOG_TAG "android.hardware.bluetooth-hci-h4" #include -#include +#include #include +#include +#include namespace android { namespace hardware { @@ -27,11 +29,20 @@ namespace bluetooth { namespace hci { size_t H4Protocol::Send(uint8_t type, const uint8_t* data, size_t length) { - int rv = WriteSafely(uart_fd_, &type, sizeof(type)); - if (rv == sizeof(type)) { - rv = WriteSafely(uart_fd_, data, length); + struct iovec iov[] = {{&type, sizeof(type)}, + {const_cast(data), length}}; + ssize_t ret = 0; + do { + ret = TEMP_FAILURE_RETRY(writev(uart_fd_, iov, sizeof(iov) / sizeof(iov[0]))); + } while (-1 == ret && EAGAIN == errno); + + if (ret == -1) { + ALOGE("%s error writing to UART (%s)", __func__, strerror(errno)); + } else if (ret == 0) { + // Nothing written :( + ALOGE("%s zero bytes written - something went wrong...", __func__); } - return rv; + return ret; } void H4Protocol::OnPacketReady() { -- cgit v1.2.3