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

[Raviteja Narayanam <rna@xilinx.com>]

> -----Original Message-----
> From: Michal Simek <michal.simek@xilinx.com>
> Sent: Tuesday, August 24, 2021 12:29 PM
> To: Marek Vasut <marex@denx.de>; linux-i2c@vger.kernel.org; Raviteja
> Narayanam <rna@xilinx.com>
> Cc: Michal Simek <michals@xilinx.com>; Shubhrajyoti Datta
> <shubhraj@xilinx.com>; Wolfram Sang <wsa@kernel.org>
> Subject: Re: [PATCH v2 0/6] i2c: xiic: Fix broken locking
> 
> +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.

Thanks a lot for the patches, Marek. 
I have tested these on our boards and they are working fine. 

I will rebase my patch series on top of this and send after rc1. 

> >
> > 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>
> >