Merge 6.3-rc6 into tty-next

[platform/kernel/linux-rpi.git] / drivers / tty / serial / 8250 / 8250_port.c

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 107bcdf..dfbc501 100644 (file)
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1903,6 +1903,17 @@ EXPORT_SYMBOL_GPL(serial8250_modem_status);
 static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir)
 {
        switch (iir & 0x3f) {
+       case UART_IIR_THRI:
+               /*
+                * Postpone DMA or not decision to IIR_RDI or IIR_RX_TIMEOUT
+                * because it's impossible to do an informed decision about
+                * that with IIR_THRI.
+                *
+                * This also fixes one known DMA Rx corruption issue where
+                * DR is asserted but DMA Rx only gets a corrupted zero byte
+                * (too early DR?).
+                */
+               return false;
        case UART_IIR_RDI:
                if (!up->dma->rx_running)
                        break;