[U-Boot] [PATCH 1/2] serial/serial_arc: add work-around of ISS bug
Alexey Brodkin
Alexey.Brodkin at synopsys.com
Sat Feb 8 07:10:01 CET 2014
Explanation is in in-lined comment.
Signed-off-by: Alexey Brodkin <abrodkin at synopsys.com>
Cc: Vineet Gupta <vgupta at synopsys.com>
Cc: Noam Camus <noamc at ezchip.com>
Cc: Tom Rini <trini at ti.com>
---
drivers/serial/serial_arc.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/drivers/serial/serial_arc.c b/drivers/serial/serial_arc.c
index e63d25d..55d0769 100644
--- a/drivers/serial/serial_arc.c
+++ b/drivers/serial/serial_arc.c
@@ -39,7 +39,23 @@ static void arc_serial_setbrg(void)
arc_console_baud = gd->cpu_clk / (gd->baudrate * 4) - 1;
writel(arc_console_baud & 0xff, ®s->baudl);
+
+#ifdef CONFIG_ARC
+ /*
+ * UART ISS(Instruction Set simulator) emulation has a subtle bug:
+ * A existing value of Baudh = 0 is used as a indication to startup
+ * it's internal state machine.
+ * Thus if baudh is set to 0, 2 times, it chokes.
+ * This happens with BAUD=115200 and the formaula above
+ * Until that is fixed, when running on ISS, we will set baudh to !0
+ */
+ if (gd->arch.running_on_hw)
+ writel((arc_console_baud & 0xff00) >> 8, ®s->baudh);
+ else
+ writel(1, ®s->baudh);
+#else
writel((arc_console_baud & 0xff00) >> 8, ®s->baudh);
+#endif
}
static int arc_serial_init(void)
--
1.8.5.3
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