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authorBen Dooks <ben.dooks@codethink.co.uk>2015-11-18 15:41:13 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-12-14 04:59:48 +0100
commit88679739012cda64b1a45ee9dea16d04380dba71 (patch)
treeed2430c80a710895825ae71e52f1382b456a6b0c /drivers/tty
parentARM: meson: serial: don't reset port on uart startup (diff)
downloadlinux-88679739012cda64b1a45ee9dea16d04380dba71.tar.xz
linux-88679739012cda64b1a45ee9dea16d04380dba71.zip
ARM: meson: serial: tx_empty fails to check for transmitter busy
The tx_empty() uart_op should only return empty if both the transmit fifo and the transmit state-machine are both idle. Add a test for the hardware's XMIT_BUSY flag. Note, this is possibly related to an issue where the port is being shutdown with paritally transmitted characters in it. Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> Reported-by: Edward Cragg <edward.cragg@codethink.co.uk> Tested-by: Carlo Caione <carlo@endlessm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/meson_uart.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
index b87eb97e5e7a..54d1b9591b8d 100644
--- a/drivers/tty/serial/meson_uart.c
+++ b/drivers/tty/serial/meson_uart.c
@@ -57,6 +57,7 @@
#define AML_UART_RX_EMPTY BIT(20)
#define AML_UART_TX_FULL BIT(21)
#define AML_UART_TX_EMPTY BIT(22)
+#define AML_UART_XMIT_BUSY BIT(25)
#define AML_UART_ERR (AML_UART_PARITY_ERR | \
AML_UART_FRAME_ERR | \
AML_UART_TX_FIFO_WERR)
@@ -100,7 +101,8 @@ static unsigned int meson_uart_tx_empty(struct uart_port *port)
u32 val;
val = readl(port->membase + AML_UART_STATUS);
- return (val & AML_UART_TX_EMPTY) ? TIOCSER_TEMT : 0;
+ val &= (AML_UART_TX_EMPTY | AML_UART_XMIT_BUSY);
+ return (val == AML_UART_TX_EMPTY) ? TIOCSER_TEMT : 0;
}
static void meson_uart_stop_tx(struct uart_port *port)