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

Wolfram Sang
2021-09-14T10:29:45Z

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On Mon, Aug 23, 2021 at 11:41:39PM +0200, 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
>

Applied to for-next, thanks everyone!

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