Instead of using below code in current drive, it seems we have to add code to follow the steps in OMAP34xx TRM to make it work. /* * TI16C752/Startech hardware flow control. FIXME: * - TI16C752 requires control thresholds to be set. * - UART_MCR_RTS is ineffective if auto-RTS mode is enabled. */ if (termios->c_cflag & CRTSCTS) efr |= UART_EFR_CTS; Followings are copied from OMAP34xx TRM. To enable and configure hardware flow control, perform the following procedure: 1. Switch to register configuration mode A to access the UARTi.MCR_REG register: a. Save the current UARTi.LCR_REG. b. Set UARTi.LCR_REG to 0x0080. 2. Enable register submode TCR_TLR to access UARTi.TCR_REG (part 1 of 2): a. Save the UARTi.MCR_REG[6] TCR_TLR value. b. Set UARTi.MCR_REG[6] TCR_TLR = 1. 3. Switch to register configuration mode B to access the UARTi.EFR_REG register: Set UARTi.LCR_REG to 0x00BF. 4. Enable register submode TCR_TLR to access the UARTi.TCR_REG register (part 2 of 2): a. Save the UARTi.EFR_REG[4] ENHANCED_EN value. b. Set the UARTi.EFR_REG[4] ENHANCED_EN bit to 1. 5. Load the new start and halt trigger values for hardware flow control: Set the following bits to the desired values: * UARTi.TCR_REG[7:4] AUTO_RTS_START * UARTi.TCR_REG[3:0] AUTO_RTS_HALT 6. Enable or disable receive and transmit hardware flow control mode and restore the UARTi.EFR_REG[4] ENHANCED_EN value saved in Step 4a. Set the following bits to the desired values: * UARTi.EFR_REG[7] AUTO_CTS_EN (0: Disable/1: Enable) * UARTi.EFR_REG[6] AUTO_RTS_EN (0: Disable/1: Enable) Restore UARTi.EFR_REG[4] ENHANCED_EN to the saved value. 7. Switch to register configuration mode A to access UARTi.MCR_REG: Set UARTi.LCR_REG to 0x0080. 8. Restore the UARTi.MCR_REG[6] TCR_TLR value saved in Step 2a. 9. Restore the UARTi.LCR_REG value saved in Step 1a. See Section 17.4.4.1.3.2, Hardware Flow Control, to choose the following values: * UARTi.EFR_REG[7] AUTO_CTS_EN * UARTi.EFR_REG[6] AUTO_RTS_EN * UARTi.TCR_REG[7:4] AUTO_RTS_START * UARTi.TCR_REG[3:0] AUTO_RTS_HALT -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
