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Message-Id: <1236321780-28718-7-git-send-email-cooloney@kernel.org> Date: Fri, 6 Mar 2009 14:42:48 +0800 From: Bryan Wu <cooloney@...nel.org> To: alan@...rguk.ukuu.org.uk Cc: linux-kernel@...r.kernel.org, Mike Frysinger <vapier.adi@...il.com>, Bryan Wu <cooloney@...nel.org> Subject: [PATCH 06/18] Blackfin Serial Driver: explain why we cannot cpu_relax() in early serial code From: Mike Frysinger <vapier.adi@...il.com> Signed-off-by: Mike Frysinger <vapier.adi@...il.com> Signed-off-by: Bryan Wu <cooloney@...nel.org> --- drivers/serial/bfin_5xx.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c index 5a163f6..de8709d 100644 --- a/drivers/serial/bfin_5xx.c +++ b/drivers/serial/bfin_5xx.c @@ -1190,6 +1190,10 @@ static __init void early_serial_putc(struct uart_port *port, int ch) unsigned timeout = 0xffff; struct bfin_serial_port *uart = (struct bfin_serial_port *)port; + /* We cannot cpu_relax() here as doing so on the BF561 relies + * on the per-cpu region being setup, and since this is early + * serial code, it may not yet be usable ... + */ while ((!(UART_GET_LSR(uart) & THRE)) && --timeout) barrier(); -- 1.5.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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