serial: tegra: check the count and read if any from dma

It is only necessary to read data from the dma buffer when the count
value is non-zero and hence, tegra_uart_copy_rx_to_tty() so only be
called when this is the case.

Although, this was being tested for in two places, there is a third
place where this was not tested. However, instead of adding another
if-statement prior to calling tegra_uart_copy_rx_to_tty(), move the test
inside the function.

Signed-off-by: Shardar Shariff Md <smohammed@nvidia.com>
[jonathanh@nvidia.com: Re-worked patch to move the check for the count
 value inside the function tegra_uart_copy_rx_to_tty(). Updated
 changelog with more commentary.]
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index 0d9d7ceb1dbbbfb872bd8e5c27d92d5d8a95c8a6..a53899c47e600083c93df1ab97e53cfc9911741f 100644 (file)
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -554,6 +554,10 @@ static void tegra_uart_copy_rx_to_tty(struct tegra_uart_port *tup,
 {
        int copied;
 
+       /* If count is zero, then there is no data to be copied */
+       if (!count)
+               return;
+
        tup->uport.icount.rx += count;
        if (!tty) {
                dev_err(tup->uport.dev, "No tty port\n");
@@ -588,8 +592,7 @@ static void tegra_uart_rx_dma_complete(void *args)
                set_rts(tup, false);
 
        /* If we are here, DMA is stopped */
-       if (count)
-               tegra_uart_copy_rx_to_tty(tup, port, count);
+       tegra_uart_copy_rx_to_tty(tup, port, count);
 
        tegra_uart_handle_rx_pio(tup, port);
        if (tty) {
@@ -626,8 +629,7 @@ static void tegra_uart_handle_rx_dma(struct tegra_uart_port *tup,
        count = tup->rx_bytes_requested - state.residue;
 
        /* If we are here, DMA is stopped */
-       if (count)
-               tegra_uart_copy_rx_to_tty(tup, port, count);
+       tegra_uart_copy_rx_to_tty(tup, port, count);
 
        tegra_uart_handle_rx_pio(tup, port);
        if (tty) {