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

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

[Chen-Yu Tsai]

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 result 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.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Cc: stable@vger.kernel.org
---
 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

Re: [PATCH] i2c: mv64xxx: continue probe when clock-frequency is missing

[Maxime Ripard]

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On Mon, Aug 25, 2014 at 11:50:19PM +0800, Chen-Yu Tsai wrote:
> 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 result 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.
> 
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> Cc: stable@vger.kernel.org

Good catch!

Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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Re: [PATCH] i2c: mv64xxx: continue probe when clock-frequency is missing

[Andrew Lunn]

On Mon, Aug 25, 2014 at 11:50:19PM +0800, Chen-Yu Tsai wrote:
> 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 result 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.
> 
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> Cc: stable@vger.kernel.org

It would be good to add

Fixes: 4c730a06c19bb ("i2c: mv64xxx: Set bus frequency to 100kHz if clock-frequency is not provided")

Acked-by: Andrew Lunn <andrew@lunn.ch>

	  Andrew


> ---
>  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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