[PATCH 2/4] i2c: rockchip: ignore i2c transfers when another transfer is running

[Sascha Hauer]

On Fri, Sep 08, 2023 at 01:55:40PM +0200, Sascha Hauer wrote:
> On Fri, Sep 08, 2023 at 01:51:32PM +0200, Sascha Hauer wrote:
> > On Fri, Sep 08, 2023 at 12:16:47PM +0200, Gerald Loacker wrote:
> > > It may happen that an i2c transfer is requested by a callback although
> > > there is an other i2c transfer running. In this case do not interrupt the
> > > transfer and return with an error.
> > > 
> > > Signed-off-by: Gerald Loacker <gerald.loacker at wolfvision.net>
> > > ---
> > >  drivers/i2c/busses/i2c-rockchip.c | 14 +++++++++++++-
> > >  1 file changed, 13 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/i2c/busses/i2c-rockchip.c b/drivers/i2c/busses/i2c-rockchip.c
> > > index 1bca3e9913..a869b9d0b7 100644
> > > --- a/drivers/i2c/busses/i2c-rockchip.c
> > > +++ b/drivers/i2c/busses/i2c-rockchip.c
> > > @@ -369,7 +369,19 @@ static int rockchip_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
> > >  {
> > >  	struct rk_i2c *i2c = to_rk_i2c(adapter);
> > >  	struct device *dev = &adapter->dev;
> > > -	int i, ret = 0;
> > > +	struct i2c_regs *regs = i2c->regs;
> > > +	int i, ret = 0, val;
> > > +
> > > +	val = readl(&regs->con);
> > > +	if (val & I2C_CON_EN) {
> > > +		val = readl(&regs->con);
> > > +		if (val & I2C_IPD_ALL_CLEAN) {
> > > +			dev_dbg(dev,
> > > +				"i2c_xfer: %d messages dropped due to pending interrupts\n",
> > > +				nmsgs);
> > > +			return -EAGAIN;
> > > +		}
> > > +	}
> > 
> > Can you have a look how this can happen? Normally this should only
> > happen if you have a heartbeat LED behind a I2C GPIO expander or some
> > other unusual setup. Adding a dump_stack() next to the dev_dbg() call
> > might give a clue.
> 
> I just realized you sent some ksz9477 along with this series. Are you
> using that in I2C mode? In that case it could be the periodic link check
> that does I2C accesses in the background.

Assuming that this is indeed your problem I have just sent a series that
could fix this issue. It's untested yet, please give it a try.

Sascha

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