On Thu, Mar 28, 2019 at 11:19:45AM +0000, Adamski, Krzysztof (Nokia - PL/Wroclaw) wrote: > Some recent commits to this driver were trying to make sure the TSS > interrupt is not generated on busy system due to 25ms timer expiring > between commands. It can still happen, however if STOP command is not > issued on time at the end of the transmission. If wait_for_completion in > axxia_i2c_xfer_msg() would not return after 25ms of getting an > interrupt, TSS will be generated and idev->err_msg will be set to > -ETIMEDOUT which will be returned from the axxia_i2c_xfer_msg(), even > though the transfer did actually succeed (STOP is automatically issued > when TSS triggers). > > Fortunately, apart from already used manual and sequence commands, the > controller also has so called auto command. It works just like manual > mode but it but an automatic STOP is issued when either transfer length > is met or NAK is received from slave device. > > This patch changes the axxia_i2c_xfer_msg() function so that auto > command is used for last message in transaction letting hardware manage > issuing STOP. TSS is disabled just after command transferring last > message finishes. Auto command, just like sequence, ends with SS > interrupt instead of SNS so handling of both had to be unified. > > The axxia_i2c_stop() is no longer needed as the transfer can only end > with following conditions: > - fully successful - then last message was send by AUTO command and STOP > was issued automatically > - NAK received - STOP is issued automatically by controller > - arbitration lost - STOP should not be issued as we don't control the > bus > - IP interrupt received - this is sent when transfer length is set to 0 > for auto/sequence command. The check for that is done before START is > send so no STOP is required > - TSS received between commands - STOP is issued by the controller > > Signed-off-by: Krzysztof Adamski <krzysztof.adamski@xxxxxxxxx> > Reviewed-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx> Changed $subject to "i2c: axxia:" and applied to for-next, thanks!
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