Re: [PATCH] i2c-davinci: Implement a bus recovery that actually works

[Mike Looijmans]

ïOn 03/09/2014 09:28 PM, Wolfram Sang wrote:
> On Fri, Feb 28, 2014 at 11:32:05AM +0100, mike.looijmans@xxxxxxxx wrote:
> > From: Mike Looijmans <milo-software@xxxxxxxxxxxxxxxxxxxxx>
> >
> > Having a board where the I2C bus locks up occasionally made it clear
> > that the bus recovery in the i2c-davinci driver will only work on
> > some boards, because on regular boards, this will only toggle GPIO
> > lines that aren't muxed to the actual pins.
> >
> > The I2C controller has the built-in capability to bit-bang its lines.
> > Use this to implement a generic recovery routine that puts the
> > controller in GPIO mode and pulse the clk lines until both SDA and
> > SCL return to a high state.
> >
> > Because the controller must be held in reset while doing so, the
> > recovery routine must re-init the controller. Since this was already
> > being done after each call to i2c_recover_bus, move that call into
> > the recovery routine as well.
> >
> > Tested on a custom board with OMAP-L138, and after this change, the
> > board can recover from chips keeping SDA low.
> >
> > Note: This is an adapted port from 2.6.37 code, and was only tested
> > with that kernel.
>
> What about using struct i2c_bus_recovery_info, so the actual recovery
> logic is taken from the core?

I never knew such a thing existed, but it sounds like a sensible thing to do.

In addition, one could also remove the "sda_pin" and "scl_pin" members from 
the platform data struct, as they no longer serve any purpose after this patch.

I won't be doing those changes though. My sponsor's budget is limited, so I'm 
just having to do the minimum I can get away with. Maybe someone from TI can 
take it further?

Mike.


Met vriendelijke groet / kind regards,

Mike Looijmans

TOPIC Embedded Systems
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