[RFC/PATCH v2 10/13] dt: omap4: panda board: set clock freq for i2c devices

G, Manjunath Kondaiah manjugk at ti.com
Wed Aug 24 05:15:13 EST 2011


Hi Benoit,

On Wed, Aug 24, 2011 at 12:33 AM, Cousson, Benoit <b-cousson at ti.com> wrote:
>> From: G, Manjunath Kondaiah<manjugk at ti.com>
>> To: devicetree-discuss at lists.ozlabs.org
>> CC: linux-omap at vger.kernel.org, linux-arm-kernel at lists.infradead.org
>>
>>
>> Update omap4 panda dts file with required clock frequencies
>> for the i2c client devices existing on panda board.
>>
>> Signed-off-by: G, Manjunath Kondaiah<manjugk at ti.com>
>> ---
>>   arch/arm/boot/dts/omap4-panda.dts |   16 ++++++++++++++++
>>   1 files changed, 16 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/arm/boot/dts/omap4-panda.dts
>> b/arch/arm/boot/dts/omap4-panda.dts
>> index c28aa95..6b831ca 100644
>> --- a/arch/arm/boot/dts/omap4-panda.dts
>> +++ b/arch/arm/boot/dts/omap4-panda.dts
>> @@ -3,4 +3,20 @@
>>   / {
>>        model = "TI OMAP4 PandaBoard";
>>        compatible = "ti,omap4-panda", "ti,omap4430";
>> +
>> +       i2c1 {
>> +               clock-frequency =<400000>;
>> +       };
>> +
>> +       i2c2 {
>> +               clock-frequency =<400000>;
>> +       };
>> +
>> +       i2c3 {
>> +               clock-frequency =<400000>;
>> +       };
>> +
>> +       i2c4 {
>> +               clock-frequency =<400000>;
>> +       };
>>   };
>
> Are you sure that this patch is setting the expected frequency?
> I see 100kHz in the boot log even with that patch.
>
> I took me some time to find the proper syntax, but in order to reference an
> existing node, you have to use &i2c1 at the top level of the file. If you
> check the output of the DTC compiler, you will see the property at the
> proper node.

Thanks for bringing this issue. This was one of query I have asked to grant in
one of the e-mail threads. Even I noticed that, it used to fetch default speed
instead of speed assigned in dts file. Let me check with your suggestion.

-Manjunath


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