On 25/08/2020 21:28, Wolfram Sang wrote:
Hi Phil,
yes, this thread is old but a similar issue came up again...
On Fri, Oct 25, 2019 at 09:14:00AM +0800, Phil Reid wrote:
So at the beginning of a new transfer, we should check if SDA (or SCL?)
is low and, if it's true, only then we should try recover the bus.
Yes, this is the proper time to do it. Remember, I2C does not define a
timeout.
FYI: Just a single poll at the start of the transfer, for it being low, will cause problems with multi-master buses.
Bus recovery should be attempted after a timeout when trying to communicate, even thou i2c doesn't define a timeout.
I'm trying to fix the designware drivers handling of this at the moment.
I wonder what you ended up with? You are right, a single poll is not
enough. It only might be if one applies the new "single-master" binding
for a given bus. If that is not present, my best idea so far is to poll
SDA for the time defined in adapter->timeout and if it is all low, then
initiate a recovery.
On my todo list still.
Our system eventually recovers at the moment and the multi-master bus
doesn't contain anything that's time critical to our systems operation.
--
Regards
Phil Reid
ElectroMagnetic Imaging Technology Pty Ltd
Development of Geophysical Instrumentation & Software
www.electromag.com.au
3 The Avenue, Midland WA 6056, AUSTRALIA
Ph: +61 8 9250 8100
Fax: +61 8 9250 7100
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