RE: [PATCH 1/2] i2c: qup: Cleared the error bits in ISR

[Abhishek Sahu]

On 2016-05-11 21:27, Sricharan wrote:
> Hi,
>
> > 1. Current QCOM I2C driver hangs when sending data to address 
> > 0x03-0x07
> > in some scenarios. The QUP controller generates invalid write in this
> > case,
> > since these addresses are reserved for different bus formats.
> >
> > 2. Also, the error handling is done by I2C QUP ISR in the case of DMA
> > mode.
> > The state need to be RESET in case of any error for clearing the 
> > available
> > data in FIFO, which otherwise leaves the BAM DMA controller in hang 
> > state.
> >
> > This patch fixes the above two issues by clearing the error bits from 
> > I2C
> > and
> > QUP status in ISR in case of I2C error, QUP error and resets the QUP 
> > state
> > to
> > clear the FIFO data.
> >
> > Signed-off-by: Abhishek Sahu <absahu@xxxxxxxxxxxxxx>
> > ---
> >  drivers/i2c/busses/i2c-qup.c | 14 ++++++++------
> >  1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-qup.c 
> > b/drivers/i2c/busses/i2c-qup.c
> > index
> > 23eaabb..8c2f1bc 100644
> > --- a/drivers/i2c/busses/i2c-qup.c
> > +++ b/drivers/i2c/busses/i2c-qup.c
> > @@ -213,14 +213,16 @@ static irqreturn_t qup_i2c_interrupt(int irq, 
> > void
> > *dev)
> >  	bus_err &= I2C_STATUS_ERROR_MASK;
> >  	qup_err &= QUP_STATUS_ERROR_FLAGS;
> >
> > -	if (qup_err) {
> > -		/* Clear Error interrupt */
> > +	/* Clear the error bits in QUP_ERROR_FLAGS */
> > +	if (qup_err)
> >  		writel(qup_err, qup->base + QUP_ERROR_FLAGS);
> > -		goto done;
> > -	}
> >
> > -	if (bus_err) {
> > -		/* Clear Error interrupt */
> > +	/* Clear the error bits in QUP_I2C_STATUS */
> > +	if (bus_err)
> > +		writel(bus_err, qup->base + QUP_I2C_STATUS);
> > +
> > +	/* Reset the QUP State in case of error */
> > +	if (qup_err || bus_err) {
> >  		writel(QUP_RESET_STATE, qup->base + QUP_STATE);
> >  		goto done;
> >  	}
>        In qup_i2c_xfer and qup_i2c_xfer_v2 state is set to RESET at the 
> end, when
>        there is no error. So would it be fine if we do it there 
> unconditionally ?
>
> Regards,
>  Sricharan

RESET the QUP state wouldn't create any issue in the case of multiple 
calls.
The existing code also RESET the QUP state for bus_err but it is not 
clearing
status bits.

--
Abhishek Sahu