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authorPaul Mundt <lethal@linux-sh.org>2008-11-13 17:46:06 +0900
committerPaul Mundt <lethal@linux-sh.org>2008-11-13 17:46:06 +0900
commit272966c070237c8cb540fe67e06df51bc6ea9cc2 (patch)
tree2937aa90cd6c972b13f0173f60e76c186111ffaf
parent5d52013cbb3d39bde9f5a6023193058eeb112e98 (diff)
serial: sh-sci: Reorder the SCxTDR write after the TDxE clear.
Under qemu there is a race between the TDxE read-and-clear and the SCxTDR write. While on hardware it can be gauranteed that the read-and-clear will happen prior to the character being written out, no such assumption can be made under emulation. As this path happens with IRQs off and the hardware itself doesn't care about the ordering, move the SCxTDR write until after the read-and-clear. Signed-off-by: Vladimir Prus <vladimir@codesourcery.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
-rw-r--r--arch/sh/kernel/early_printk.c2
-rw-r--r--drivers/serial/sh-sci.c2
2 files changed, 2 insertions, 2 deletions
diff --git a/arch/sh/kernel/early_printk.c b/arch/sh/kernel/early_printk.c
index 98a29a78230..a952dcf9999 100644
--- a/arch/sh/kernel/early_printk.c
+++ b/arch/sh/kernel/early_printk.c
@@ -85,9 +85,9 @@ static void scif_sercon_putc(int c)
while (((sci_in(&scif_port, SCFDR) & EPK_FIFO_BITS) >= EPK_FIFO_SIZE))
;
- sci_out(&scif_port, SCxTDR, c);
sci_in(&scif_port, SCxSR);
sci_out(&scif_port, SCxSR, 0xf3 & ~(0x20 | 0x40));
+ sci_out(&scif_port, SCxTDR, c);
while ((sci_in(&scif_port, SCxSR) & 0x40) == 0)
;
diff --git a/drivers/serial/sh-sci.c b/drivers/serial/sh-sci.c
index 518c0321e4d..165fc010978 100644
--- a/drivers/serial/sh-sci.c
+++ b/drivers/serial/sh-sci.c
@@ -144,9 +144,9 @@ static void put_char(struct uart_port *port, char c)
status = sci_in(port, SCxSR);
} while (!(status & SCxSR_TDxE(port)));
- sci_out(port, SCxTDR, c);
sci_in(port, SCxSR); /* Dummy read */
sci_out(port, SCxSR, SCxSR_TDxE_CLEAR(port));
+ sci_out(port, SCxTDR, c);
spin_unlock_irqrestore(&port->lock, flags);
}