From 272966c070237c8cb540fe67e06df51bc6ea9cc2 Mon Sep 17 00:00:00 2001 From: Paul Mundt Date: Thu, 13 Nov 2008 17:46:06 +0900 Subject: [PATCH] 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 Signed-off-by: Paul Mundt --- arch/sh/kernel/early_printk.c | 2 +- drivers/serial/sh-sci.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/sh/kernel/early_printk.c b/arch/sh/kernel/early_printk.c index 98a29a782301..a952dcf9999d 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 518c0321e4d3..165fc010978c 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); } -- 2.20.1