Fix potential deadlock in PL011 init function

The PL011 initialization function disables the UART, flushes the FIFO
and waits for the current character to be transmitted before applying
the configuration and enabling the UART. This waiting might result in
a deadlock if the FIFO is disabled while another CPU is printing a
message since the flush of FIFO will never finish.

This patch fixes the problem by removing the flush operation and the
loop for last character completion from the initialization function.
The UART is disabled, configured and enabled again.

Change-Id: I1ca0b6bd9f352c12856f10f174a9f6eaca3ab4ea

diff --git a/drivers/arm/pl011/pl011_console.S b/drivers/arm/pl011/pl011_console.S
index f29f895b595c20b0b86479513c8a4a6b5161706e..5e97e9119d3635431b3d818001a08422cf4033f1 100644 (file)
--- a/drivers/arm/pl011/pl011_console.S
+++ b/drivers/arm/pl011/pl011_console.S
@@ -69,15 +69,6 @@ func console_core_init
        mov     w4, #PL011_UARTCR_UARTEN
        bic     w3, w3, w4
        str     w3, [x0, #UARTCR]
-       /* Flush the transmit FIFO */
-       ldr     w3, [x0, #UARTLCR_H]
-       mov     w4, #PL011_UARTLCR_H_FEN
-       bic     w3, w3, w4
-       str     w3, [x0, #UARTLCR_H]
-       /* Wait for the end of Tx of current character */
-busy_loop:
-       ldr     w3, [x0, #UARTFR]
-       tbnz    w3, #PL011_UARTFR_BUSY_BIT, busy_loop
        /* Program the baudrate */
        /* Divisor =  (Uart clock * 4) / baudrate */
        lsl     w1, w1, #2