Subject: [PATCH v2] I2C: OMAP: Recover from Bus Busy condition

From: [email-masked] (Kevin Hilman)
Date: Wed, 11 Jan 2012 14:28:20 -0800

Shubhrajyoti D <[email-masked]> writes:

> From: Vikram Pandita <[email-masked]>
>
> In case a peripheral is driving SDA bus low (ie. a start condition), provide
> a constant clock output using the test mode of the OMAP I2C controller to
> try and clear the bus. Soft reset I2C controller after attempting the bus clear
> to ensure that controller is in a good state.
>
> Based upon Vikram Pandita's patch from TI Android 3.0 kernel and modified for
> mainline by Jon Hunter. 
>
> A couple differences from the original patch ...
> 1. Add a new function for bus clear
> 2. Ensure that the CON.I2C_EN bit is set when using the SYSTEST feature to
>    output a permanent clock. This bit needs to be set and tpyically it would
>    be set by the unidle function but this is not the case for all OMAP
>    generations.
> 3. Program the SYSTEST setting only the bits we care about. However, restore
>    SYSTEST registers to there original state as some OMAP generations do not
>    implement perform a soft-reset.
> 4. Clear the CON register after performing the bus clear, so when we call the
>    init function the controller is disabled and the init function will
>    re-enable later.
>
> Cc:  Kevin Hilman <[email-masked]>
> Signed-off-by: Vikram Pandita <[email-masked]>
> Signed-off-by: Jon Hunter <[email-masked]>
> Signed-off-by: Shubhrajyoti D <[email-masked]>
> ---
> Original patch can be found here:
> http://git.omapzoom.org/?p=kernel/omap.git;a=commit;h=a2ab04192ba25e60f95ba1ff3af5601a2d7b5bd1
> applies on Kevin's for_3.3/i2c/misc

Please also explain how this was tested, and on what platforms.

Thanks,

Kevin