Implement logical address allocation logic for HDMI CEC.
Logical address in CEC is to distinguish each logical device from others. In order to allocate logical address for new device, CEC sends <Polling Message> to CEC bus. <Polling Message> is a CEC message which has the same address for both source and destination without body frame. (10bits). CEC allows one and more logical address for a device type. For example, there are 3 logical address defined for recorder device(1, 2, 9). Among logical address candidates for the given device type, CEC scans first the previous logical address (preferred logical address) of device. If a device has not been allocated any logical address, preferred address will be 15 (Unregistered), which means scan address from the minimum address number of type. For example for recorder device, it starts from 1. If no devices acks to the <Polling Message> during scan, it will be the logical address of the device. Since logical address is determined by a series of sending <Polling Message> it happens in IO thread with separate allocate logical address message instead of individual sendCommand message. Along with this, updated ADDR_FREE_USE(14) to ADDR_SPECIFIC_USE(14) which is revised name on HDMI 1.4. Change-Id: Ic96dcdbe4aaa3789cfed0352a88ca75369335a98
Loading
Please register or sign in to comment