Messages in this thread | | | Date | Mon, 10 Mar 2014 11:24:55 +0100 | From | Mike Looijmans <> | Subject | Re: [PATCH] i2c-davinci: Handle signals gracefully |
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On 03/09/2014 09:21 PM, Wolfram Sang wrote: > On Thu, Jan 09, 2014 at 12:11:25PM +0100, Mike Looijmans wrote: >> When a signal is caught while the i2c-davinci bus driver is transferring, >> the drive just "abandons" the transfer and leaves the controller to fend >> for itself. The next I2C transaction will find the controller in an >> undefined state and often results in a stream of "initiating i2c bus recovery" >> messages until the controller arrives in a defined state. This behaviour >> also sends out "half" or possibly even mixed messages to I2C client >> devices which may put them in an undesired state as well. >> >> This patch fixes this issue by always attempting to finish the current >> transaction, and then check on a pending signal. It either reports >> success if all data has been transferred, or it returns failure when >> the transaction was aborted. This keeps the controller in a defined >> state, and is also much friendlier towards client devices, because >> it will only send complete messages. > > Even more, you should complete the whole transfer. There are devices > where things can really go wrong if you send a half-complete command and > then start with the next one. So, not checking signals at all is the way > to go for I2C drivers. There is some cruft left, so I am happy about > patches fixing that, with testing on real HW. Like yours here.
I agree.
I know the Zynq (using a cadence controller) also lets signals interrupt I2C transfers, so I'll propose a patch to Xilinx and CC to you and linux-i2c to completely remove signal handling from that driver as well.
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@topic.nl Website: www.topic.nl
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