https://github.com/torvalds/linux
Revision 2bed8a8e70729f996af92042d3ad0f11870acc1f authored by Daniel Jedrychowski on 11 December 2016, 22:18:28 UTC, committed by Greg Kroah-Hartman on 11 January 2017, 07:35:17 UTC
When in RS485 emulation mode, __do_stop_tx_rs485() calls serial8250_clear_fifos(). This not only clears the FIFOs, but also sets all bits in their control register (UART_FCR) to 0. One of the effects of this is the disabling of the FIFOs, which turns them into single-byte holding registers. The rest of the driver doesn't know this, which results in the lions share of characters passed into a write call to be dropped. (I can supply logic analyzer screenshots if necessary) This fix replaces the serial8250_clear_fifos() call to serial8250_clear_and_reinit_fifos() - this prevents the "dropped characters" issue from manifesting again while retaining the requirement of clearing the RX FIFO after transmission if the SER_RS485_RX_DURING_TX flag is disabled. Signed-off-by: Daniel Jedrychowski <avistel@gmail.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 parent c130b66
Tip revision: 2bed8a8e70729f996af92042d3ad0f11870acc1f authored by Daniel Jedrychowski on 11 December 2016, 22:18:28 UTC
Clearing FIFOs in RS485 emulation mode causes subsequent transmits to break
Clearing FIFOs in RS485 emulation mode causes subsequent transmits to break
Tip revision: 2bed8a8
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