Re: [PATCH v2 0/6] i2c: xiic: Fix broken locking

Michal Simek
2021-08-24T06:58:53Z

+ravi

On 8/23/21 11:41 PM, Marek Vasut wrote:
> Booting ZynqMP with XIIC I2C driver shows multitude of race conditions
> in the XIIC driver. This is because locking is completely missing from
> the driver, and there are odd corner cases where the hardware behaves
> strangely.
>
> Most of these races could be triggered easily when booting on SMP
> machines, like the ZynqMP which has up to 4 cores. It is sufficient
> for the interrupt handler to run on another core than xiic_start_xfer
> and the driver fails completely.
>
> This does not add support for long transfers, this only fixes the
> driver to be usable at all instead of being completely broken.
>
> The V2 fixes a few remaining details which cropped up in deployment
> over the last year or so, so I believe the result should be reasonably
> well tested.
>
> Marek Vasut (6):
> i2c: xiic: Fix broken locking on tx_msg
> i2c: xiic: Drop broken interrupt handler
> i2c: xiic: Defer xiic_wakeup() and __xiic_start_xfer() in
> xiic_process()
> i2c: xiic: Switch from waitqueue to completion
> i2c: xiic: Only ever transfer single message
> i2c: xiic: Fix RX IRQ busy check
>
> drivers/i2c/busses/i2c-xiic.c | 161 +++++++++++++++-------------------
> 1 file changed, 69 insertions(+), 92 deletions(-)
>
> Cc: Michal Simek <michal.simek@xilinx.com>
> Cc: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
> Cc: Wolfram Sang <wsa@kernel.org>
>