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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>
This commit is contained in:
Ben Dooks 2015-11-18 14:41:13 +00:00 committed by Greg Kroah-Hartman
parent 00661dd855
commit 8867973901
1 changed files with 3 additions and 1 deletions
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4
drivers/tty/serial/meson_uart.c
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@ -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)