[PATCH v5 0/2] Cadence I2C driver fixes

Harini Katakam harinikatakamlinux at gmail.com
Mon Jan 12 02:08:25 PST 2015


Any further comments on this?


On Fri, Dec 12, 2014 at 9:48 AM, Harini Katakam <harinik at xilinx.com> wrote:
> 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 transfers are done such that transfer_size never becomes zero.
> - timeout register value is increased (even though the driver doesn't use this).
> - A check is performed to see if there is 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 (2):
>   i2c: cadence: Handle > 252 byte transfers
>   i2c: cadence: Check for errata condition involving master receive
>  drivers/i2c/busses/i2c-cadence.c |  185 +++++++++++++++++++++++---------------
>  1 file changed, 112 insertions(+), 73 deletions(-)
> --

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