linux-kernel - [PATCH v5] serial: 8250_dw: fix wrong logic in dw8250_check

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Date:	Mon, 2 May 2016 17:19:46 +0800
From:	Kefeng Wang <wangkefeng.wang@...wei.com>
To:	<noamc@...hip.com>, <gregkh@...uxfoundation.org>
CC:	<andriy.shevchenko@...ux.intel.com>,
	<heikki.krogerus@...ux.intel.com>, <linux-serial@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <guohanjun@...wei.com>,
	<wangkefeng.wang@...wei.com>
Subject: [PATCH v5] serial: 8250_dw: fix wrong logic in dw8250_check_lcr()

Commit cdcea058e510 ("serial: 8250_dw: Avoid serial_outx code duplicate
with new dw8250_check_lcr()") introduce a wrong logic when write val to
LCR reg. When CONFIG_64BIT enabled, __raw_writeq is used unconditionally.

The __raw_readq/__raw_writeq is introduced by commit bca2092d7897 ("serial:
8250_dw: Use 64-bit access for OCTEON.") for OCTEON.

So for 64BIT && !PORT_OCTEON, we better to use coincident write function.

Fixes: cdcea058e510("serial: 8250_dw: Avoid serial_outx code duplicate with new dw8250_check_lcr()")
Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---

Changes since v4:
- Update change log, suggested by Andy Shevchenko.
Changes since v3:
- Add patch change log, suggested by Greg Kroah-Hartman.
Changes since v2:
- Add #ifdef CONFIG_64BIT back, ensure it can be built under configuration lacking readq/writeq.
Changes since v1:
- Repace '#ifdef CONFIG_64BIT' with IS_ENABLED(CONFIG_64BIT).
- Enrich patch log, and add Fixes tag.
  

 drivers/tty/serial/8250/8250_dw.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index a3fb95d..47d1f3e 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -104,15 +104,16 @@ static void dw8250_check_lcr(struct uart_port *p, int value)
 		dw8250_force_idle(p);
 
 #ifdef CONFIG_64BIT
-		__raw_writeq(value & 0xff, offset);
-#else
+		if (p->type == PORT_OCTEON)
+			__raw_writeq(value & 0xff, offset);
+		else
+#endif
 		if (p->iotype == UPIO_MEM32)
 			writel(value, offset);
 		else if (p->iotype == UPIO_MEM32BE)
 			iowrite32be(value, offset);
 		else
 			writeb(value, offset);
-#endif
 	}
 	/*
 	 * FIXME: this deadlocks if port->lock is already held
-- 
2.6.0.GIT