From: Shardar Shariff Md <smoham...@nvidia.com>

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 <smoham...@nvidia.com>
[jonath...@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 <jonath...@nvidia.com>
---
 drivers/tty/serial/serial-tegra.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/serial-tegra.c 
b/drivers/tty/serial/serial-tegra.c
index 0d9d7ceb1dbb..a53899c47e60 100644
--- 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) {
-- 
1.9.1

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