[Xen-devel] [PATCH] drivers/exynos4210: Wait the end of last transfer before initializing the UART

[Julien Grall <julien.grall@xxxxxxxxxx>]

When early printk is enabled by the user, it's possible to loose the last
characters if the UART is initialized without waiting that the last transfer
was completed.

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
---
 xen/drivers/char/exynos4210-uart.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/xen/drivers/char/exynos4210-uart.c 
b/xen/drivers/char/exynos4210-uart.c
index f7971da..13758d4 100644
--- a/xen/drivers/char/exynos4210-uart.c
+++ b/xen/drivers/char/exynos4210-uart.c
@@ -104,6 +104,12 @@ static void __init exynos4210_uart_init_preirq(struct 
serial_port *port)
     unsigned int divisor;
     uint32_t ulcon;
 
+#ifdef EARLY_PRINTK
+    /* Flush the UART */
+    while ( !(exynos4210_read(uart, UTRSTAT) &  UTRSTAT_TX_EMPTY) )
+        cpu_relax();
+#endif
+
     /* reset, TX/RX disables */
     exynos4210_write(uart, UCON, 0);
 
-- 
1.7.10.4


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