Tomasz,
On Mon, Apr 14, 2014 at 3:38 PM, Tomasz Figa <tomasz.figa@xxxxxxxxx> wrote:
> Hi Doug,
>
>
> On 15.04.2014 00:30, Doug Anderson wrote:
>>
>> Sachin,
>>
>> On Mon, Apr 14, 2014 at 6:16 AM, Sachin Kamat <sachin.kamat@xxxxxxxxxx>
>> wrote:
>>>
>>> From: Doug Anderson <dianders@xxxxxxxxxxxx>
>>
>>
>> I probably wouldn't have bothered giving me authorship since this
>> isn't exactly a clean patch from the chromium tree (you pulled the
>> proper pieces yourself, did the commit message yourself, etc). ...but
>> I appreciate the thought and as far as I know setting the "author" in
>> cases like this is a bit of a judgement call...
>>
>> The Signed-off-by is certainly correct. ;)
>>
>>>
>>> Added i2c-arbitrator pinctrl node to Snow board.
>>>
>>> Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
>>> Signed-off-by: Sachin Kamat <sachin.kamat@xxxxxxxxxx>
>>> ---
>>> arch/arm/boot/dts/exynos5250-snow.dts | 19 +++++++++++++++++++
>>> 1 file changed, 19 insertions(+)
>>
>>
>> This matches what's in our tree and and is what people are using, so:
>>
>> Reviewed-by: Doug Anderson <dianders@xxxxxxxxxxxx>
>>
>>
>>> diff --git a/arch/arm/boot/dts/exynos5250-snow.dts
>>> b/arch/arm/boot/dts/exynos5250-snow.dts
>>> index 1ce1088..32715b3 100644
>>> --- a/arch/arm/boot/dts/exynos5250-snow.dts
>>> +++ b/arch/arm/boot/dts/exynos5250-snow.dts
>>> @@ -39,6 +39,22 @@
>>> };
>>> };
>>>
>>> + pinctrl@13400000 {
>>> + arb_their_claim: arb-their-claim {
>>> + samsung,pins = "gpe0-4";
>>> + samsung,pin-function = <0>;
>>> + samsung,pin-pud = <3>;
>>> + samsung,pin-drv = <0>;
>>> + };
>>> +
>>> + arb_our_claim: arb-our-claim {
>>> + samsung,pins = "gpf0-3";
>>> + samsung,pin-function = <1>;
>>> + samsung,pin-pud = <0>;
>>> + samsung,pin-drv = <0>;
>>> + };
>>
>>
>> It's odd to me that one of these has a pullup but not the other, but I
>> think that's because the arbitration lines ended up using some other
>> signals that were originally hooked up for other usage. Certainly the
>> pullups / pulldowns match what's in our tree and also match what we
>> had in the original shipping 3.4 kernel.
>
>
> Just a wild guess, but probably the input needs a pull-up, while obviously
> the output doesn't. I don't have much idea about the arbitration thing
> happening on snow, so I can't say much about this series. (Maybe description
> of patch 1/4 should be saying a bit more about the meaning of this?)
Right, of course. I'm not sure quite what I was thinking. I think I
was getting confused since these go through level converters and my
brain was in open drain mode. ...but looking at this again this looks
reasonable.
I think the whole discussion of arbitration was from a long time ago.
I think it's fairly well documented in the "i2c-arb-gpio-challenge"
driver.
Basically it looks like Sachin is getting pinctrl stuff matched up
properly for the device tree that's upstream.
-Doug
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