tty: serial: qcom_geni_serial: Remove unnecessary memory barrier

While initiating TX, only the register reads need to be ordered. The
register write order either is achieved due to data dependency or is
not required.

Use readl to achieve the read order and remove the unnecessary barrier.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>
Reviewed-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index d114b67be409714d0e25c55299ff63d286979274..3e9de6c780d30d7ea0f178f05d2b85ebd2cd62b7 100644 (file)
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -417,20 +417,18 @@ static void qcom_geni_serial_start_tx(struct uart_port *uport)
        u32 status;
 
        if (port->xfer_mode == GENI_SE_FIFO) {
-               status = readl_relaxed(uport->membase + SE_GENI_STATUS);
+               /*
+                * readl ensures reading & writing of IRQ_EN register
+                * is not re-ordered before checking the status of the
+                * Serial Engine.
+                */
+               status = readl(uport->membase + SE_GENI_STATUS);
                if (status & M_GENI_CMD_ACTIVE)
                        return;
 
                if (!qcom_geni_serial_tx_empty(uport))
                        return;
 
-               /*
-                * Ensure writing to IRQ_EN & watermark registers are not
-                * re-ordered before checking the status of the Serial
-                * Engine and TX FIFO
-                */
-               mb();
-
                irq_en = readl_relaxed(uport->membase + SE_GENI_M_IRQ_EN);
                irq_en |= M_TX_FIFO_WATERMARK_EN | M_CMD_DONE_EN;
 
@@ -894,7 +892,7 @@ static void qcom_geni_serial_set_termios(struct uart_port *uport,
 
 static unsigned int qcom_geni_serial_tx_empty(struct uart_port *uport)
 {
-       return !readl_relaxed(uport->membase + SE_GENI_TX_FIFO_STATUS);
+       return !readl(uport->membase + SE_GENI_TX_FIFO_STATUS);
 }
 
 #ifdef CONFIG_SERIAL_QCOM_GENI_CONSOLE