On 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
Eindhovenseweg 32-C, NL-5683 KH Best
Postbus 440, NL-5680 AK Best
Telefoon: (+31) (0) 499 33 69 79
Telefax: (+31) (0) 499 33 69 70
E-mail: mike.looijmans@xxxxxxxx
Website: www.topic.nl
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