This series implements workarounds for some bugs in Cadence I2C controller. - The I2C controller when configured in Master Mode generates invalid read transactions. When HOLD bit is set and HW timeout occurs, invalid read transactions are generated on the bus. This will affect repeated start conditions and large data transfer condtions where transfer_size_register has to be updated again. The transfer size register rolls over erroneously under these conditions. Note that this HW timeout cannot be disabled even if the interrupt is unused. Errata link: http://www.xilinx.com/support/answers/61664.html -The I2C controller when configured in Master Mode is the missing master completion interrupt. During repeated start condition, the driver has to set the HOLD bit for the set of transfer being done together and clear the HOLD bit just before the last transfer. But the controller does not indicate completion when a read/receive transfer is done if the HOLD bit is set. This affects all repeated start operation where a read/receive transfer is not the last transfer. Errata link: http://www.xilinx.com/support/answers/61665.html To address the above, - >252 byte transfer are done such that transfer_size never becomes zero. - timeout register value is increased (even though the driver doesn't use this). - repeated start is defeatured based on a devicetree input. This input is because repeated start is required as part of protocol for some slave devices (not just to retain control in a multi-master scenario). The driver works as expected with these devices and hence the defeature is optional in such cases. - In case user chooses not to de-feature repeated start, then a check is performed to see if there any transfer following a read/receive transfer in the set of messages using repeated start. An error is returned in such cases because if we proceed, completion interrupt is never obtained and a SW timeout will occur. Harini Katakam (1): i2c: cadence: Handle > 252 byte transfers Vishnu Motghare (3): i2c: cadence: Set the hardware time-out register to maximum value devicetree: bindings: Add defeature-repeated-start property for Cadence I2C i2c: cadence: Defeature repeated start based on devicetree property .../devicetree/bindings/i2c/i2c-cadence.txt | 11 ++ drivers/i2c/busses/i2c-cadence.c | 200 +++++++++++--------- 2 files changed, 125 insertions(+), 86 deletions(-) -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
