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[v1,08/11] char/cadence_uart: Fix can_receive logic

Message ID f8c313fc6058d16082453324ed4ef54e2a378220.1387244071.git.peter.crosthwaite@xilinx.com
State New
Headers show

Commit Message

Peter Crosthwaite Dec. 17, 2013, 1:44 a.m. UTC 
The can_receive logic was only taking into account the RxFIFO
occupancy. RxFIFO population is only used for the echo and normal modes
however. Improve the logic to correctly return the true number of
receivable characters based on the current mode:

Normal mode: RxFIFO vacancy.
Remote loopback: TxFIFO vacancy.
Echo mode: The min of the TxFIFO and RxFIFO vacancies.
Local Loopback: Return non-zero (to implement droppage)

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
---

 hw/char/cadence_uart.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
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Patch

diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c
index f28e503..85e9a00 100644
--- a/hw/char/cadence_uart.c
+++ b/hw/char/cadence_uart.c
@@ -233,8 +233,16 @@  static void uart_parameters_setup(UartState *s)
 static int uart_can_receive(void *opaque)
 {
     UartState *s = (UartState *)opaque;
+    int ret = MAX(RX_FIFO_SIZE, TX_FIFO_SIZE);
+    uint32_t ch_mode = s->r[R_MR] & UART_MR_CHMODE;
 
-    return RX_FIFO_SIZE - s->rx_count;
+    if (ch_mode == NORMAL_MODE || ch_mode == ECHO_MODE) {
+        ret = MIN(ret, RX_FIFO_SIZE - s->rx_count);
+    }
+    if (ch_mode == REMOTE_LOOPBACK || ch_mode == ECHO_MODE) {
+        ret = MIN(ret, TX_FIFO_SIZE - s->tx_count);
+    }
+    return ret;
 }
 
 static void uart_ctrl_update(UartState *s)