1.Does the driver for this chip has an armv6 version? arm-linux-gcc?
>> You can find the drivers available for the part in the link: http://www.cypress.com/documentation/software-and-drivers/usb-serial-software-development-kit
2. I wanna know its performance when using as i2c master? When i need to send a block of bytes, will this chip have a big delay between two bytes causing by read the ack back to cpu and let cpu decide if the transmission is correct? This will waste a lot of time.
>> There will not be big delay between two bytes when you send/receive blocks of data.
3. Does this chip support multi thread? if i call a function to write sth, two write function can be called simultaneously without mutex? As this function utilizes one usb, so i have a concern about that
>> Although, the part utilizes one USB, you can perform two simultaneous writes as the endpoints associated to channels are different.