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serial: sirf: fix system hung on console log output 

A corner case exists in the current driver. if an app opens the console
device, and before writing to console device, and there are huge kernel
ogs to print out, system will hang on
sirfsoc_uart_console_putchar:
while (rd_regl(port, ureg->sirfsoc_tx_fifo_status) &
	ufifo_st->ff_full(port->line))
	cpu_relax();
as in sirfsoc_uart_startup(), the driver assigns tx_fifo_op to 0 will stop
TX FIFO, this loop will be endless.

Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Qipan Li 2015-05-26 09:35:58 +00:00 committed by Greg Kroah-Hartman
parent ba02406e9b
commit 326707ed88
1 changed files with 1 additions and 1 deletions
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2
drivers/tty/serial/sirfsoc_uart.c
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@ -272,6 +272,7 @@ static void sirfsoc_uart_start_tx(struct uart_port *port)
if (sirfport->uart_reg->uart_type == SIRF_USP_UART)
wr_regl(port, ureg->sirfsoc_tx_rx_en, rd_regl(port,
ureg->sirfsoc_tx_rx_en) | SIRFUART_TX_EN);
wr_regl(port, ureg->sirfsoc_tx_fifo_op, SIRFUART_FIFO_STOP);
sirfsoc_uart_pio_tx_chars(sirfport, port->fifosize);
wr_regl(port, ureg->sirfsoc_tx_fifo_op, SIRFUART_FIFO_START);
if (!sirfport->is_atlas7)
@ -1117,7 +1118,6 @@ static int sirfsoc_uart_startup(struct uart_port *port)
SIRFSOC_USP_ENDIAN_CTRL_LSBF |
SIRFSOC_USP_EN);
wr_regl(port, ureg->sirfsoc_tx_fifo_op, SIRFUART_FIFO_RESET);
wr_regl(port, ureg->sirfsoc_tx_fifo_op, 0);
wr_regl(port, ureg->sirfsoc_rx_fifo_op, SIRFUART_FIFO_RESET);
wr_regl(port, ureg->sirfsoc_rx_fifo_op, 0);
wr_regl(port, ureg->sirfsoc_tx_fifo_ctrl, SIRFUART_FIFO_THD(port));