linux-kernel - [PATCH v2] i2c: mv64xxx: continue probe when clock-frequency is missing

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Message-Id: <1409581693-15943-1-git-send-email-wens@csie.org>
Date:	Mon,  1 Sep 2014 22:28:13 +0800
From:	Chen-Yu Tsai <wens@...e.org>
To:	Wolfram Sang <wsa@...-dreams.de>
Cc:	Chen-Yu Tsai <wens@...e.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Gregory CLEMENT <gregory.clement@...e-electrons.com>,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, Andrew Lunn <andrew@...n.ch>,
	linux-sunxi@...glegroups.com, stable@...r.kernel.org
Subject: [PATCH v2] i2c: mv64xxx: continue probe when clock-frequency is missing

The "clock-frequency" DT property is listed as optional, However,
the current code stores the return value of of_property_read_u32 in
the return code of mv64xxx_of_config, but then forgets to clear it
after setting the default value of "clock-frequency". It is then
passed out to the main probe function, resulting in a probe failure
when "clock-frequency" is missing.

This patch checks and then throws away the return value of
of_property_read_u32, instead of storing it and having to clear it
afterwards.

This issue was discovered after the property was removed from all
sunxi DTs.

Fixes: 4c730a06c19bb ("i2c: mv64xxx: Set bus frequency to 100kHz if clock-frequency is not provided")
Signed-off-by: Chen-Yu Tsai <wens@...e.org>
Cc: stable@...r.kernel.org
Acked-by: Andrew Lunn <andrew@...n.ch>
Acked-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
---
Changes in v2:

 - Added Fixes tag, and Acked-bys from Andrew and Maxime.
 - Slightly refined commit message to be clear what we're throwing away.
---
 drivers/i2c/busses/i2c-mv64xxx.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 6dc5ded..2f64273 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -746,8 +746,7 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
 	}
 	tclk = clk_get_rate(drv_data->clk);
 
-	rc = of_property_read_u32(np, "clock-frequency", &bus_freq);
-	if (rc)
+	if (of_property_read_u32(np, "clock-frequency", &bus_freq))
 		bus_freq = 100000; /* 100kHz by default */
 
 	if (!mv64xxx_find_baud_factors(bus_freq, tclk,
-- 
2.1.0

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