Messages in this thread | | | Date | Tue, 16 Jul 2013 17:33:47 +0800 | From | Hein Tibosch <> | Subject | Re: [PATCH] i2c-omap: always send stop after nack |
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On 7/16/2013 5:03 PM, Felipe Balbi wrote: > Hi, > > On Tue, Jul 16, 2013 at 04:19:35PM +0800, Hein Tibosch wrote: >> Hi Vikram, >> >> On a OMAP4460, i2c-bus-3: >> >> A driver (lm75) is causing many 'timeout waiting for bus ready' errors. >> SDA remains high (as it should), but SCL remains low after a NACK. >> The bus becomes _unusable for other clients_. >> >> While probing, "lm75" writes a command, followed by a read + stop, >> but the write command is NACK'd. The chip does accept other writes/reads, >> it just refuses to ack invalid commands. >> >> Can you tell me if the patch below would make any sense? Or is it the >> responsibility of the client to reset the i2c_smbus? > patch below breaks repeated start. Hi,
No, after the NACK, no more commands are being processed, including a repeated start. omap_i2c_xfer() returns -EREMOTEIO without ever freeing the bus.
The bus is left in an impossible state with SCL constantly low and all next commands (to different chips) will therefore get a -ETIMEDOUT
With this patch, the bus will become idle again and new commands can be processed normally
Hein
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