1 files changed, 14 insertions, 1 deletions

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index cede93876649..925eb8813a45 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1595,13 +1595,26 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
                         old_cr &= ~ST_UART011_CR_OVSFACT;
         }
 
+        /*
+         * Workaround for the ST Micro oversampling variants to
+         * increase the bitrate slightly, by lowering the divisor,
+         * to avoid delayed sampling of start bit at high speeds,
+         * else we see data corruption.
+         */
+        if (uap->vendor->oversampling) {
+                if ((baud >= 3000000) && (baud < 3250000) && (quot > 1))
+                        quot -= 1;
+                else if ((baud > 3250000) && (quot > 2))
+                        quot -= 2;
+        }
         /* Set baud rate */
         writew(quot & 0x3f, port->membase + UART011_FBRD);
         writew(quot >> 6, port->membase + UART011_IBRD);
 
         /*
          * ----------v----------v----------v----------v-----
-         * NOTE: MUST BE WRITTEN AFTER UARTLCR_M & UARTLCR_L
+         * NOTE: lcrh_tx and lcrh_rx MUST BE WRITTEN AFTER
+         * UART011_FBRD & UART011_IBRD.
          * ----------^----------^----------^----------^-----
          */
         writew(lcr_h, port->membase + uap->lcrh_rx);