[U-Boot] [PATCH 1/3] i2c: tegra: use repeated start for reads

[Stephen Warren <swarren@wwwdotorg.org>]

On 07/02/2014 10:34 PM, Heiko Schocher wrote:
> Hello Stephen,
> 
> Am 02.07.2014 20:37, schrieb Stephen Warren:
>> On 06/25/2014 10:57 AM, Stephen Warren wrote:
>>> From: Stephen Warren<swarren@nvidia.com>
>>>
>>> I2C read transactions are typically implemented as follows:
>>>
>>> START(write) address REPEATED_START(read) data... STOP
>>>
>>> However, Tegra's I2C driver currently implements reads as follows:
>>>
>>> START(write) address STOP START(read) data... STOP
>>>
>>> This sequence confuses at least the AS3722 PMIC on the Jetson TK1 board,
>>> leading to corrupted read data in some cases. Fix the driver to chain
>>> the transactions together using repeated starts to solve this.
>>
>> Heiko, do these patches look good?
> 
> Yes, they look good to me... Hmm.. as you ask, I think you want to have
> them in v2014.07 ? As it is a bugfix it should go into it, but as it
> also changes the behaviour of the driver, I am unsure if it can go in
> so close before the new release ... some Tested-by would be nice ...

Sorry for the slow response; I was on vacation. I see the patches made
it into the release, which should be fine. The I2C functionality is
likely used very little, so even if there were problems with the patch,
the fallout from it would be minimal.

> I applied them to the u-boot-i2c.git tree, and if nobody objects
> against them, I send tomorrow a pull request to Tom.

Thanks.