Re: [PATCH v3 2/4] i2c: omap: implement workaround for handling invalid BB-bit values

[Felipe Balbi]

On Mon, Nov 24, 2014 at 11:08:48AM -0800, Kevin Hilman wrote:
> On Sat, Nov 22, 2014 at 11:47 AM, Alexander Kochetkov
> <al.kochet@xxxxxxxxx> wrote:
> > In a multimaster environment, after IP software reset, BB-bit value doesn't
> > correspond to the current bus state. It may happen what BB-bit will be 0,
> > while the bus is busy due to another I2C master activity.
> >
> > Any transfer started when BB=0 and bus is busy wouldn't be completed by IP
> > and results in controller timeout. More over, in some cases IP could
> > interrupt another master's transfer and corrupt data on wire.
> >
> > The commit implement method allowing to prevent IP from entering into
> > "controller timeout" state and from "data corruption" state.
> >
> > The one drawback is the need to wait for 10ms before the first transfer.
> >
> > Tested on Beagleboard XM C.
> > Tested on BBB and AM437x Starter Kit by Felipe Balbi.
> >
> > Signed-off-by: Alexander Kochetkov <al.kochet@xxxxxxxxx>
> > Tested-by: Felipe Balbi <balbi@xxxxxx>
> > Reviewed-by: Felipe Balbi <balbi@xxxxxx>
> 
> This patch recently hit linux-next (as commit 903c3859f77f) and boot
> breakage[1] in next-20141124 on OMAP3530 Beagle and Overo/Tobi boards
> was bisected down to this commit.
> 
> Kevin
> 
> [1] http://status.armcloud.us/boot/?next-20141124&omap

btw, based on Kevin's boot test, only OMAP3530 is failing.

-- 
balbi

Attachment: signature.asc
Description: Digital signature