Re: [PATCH v4 3/3] i2c: qcom-geni: Add bus recovery support for GPI DMA mode

[Aniket RANDIVE]

On 11/3/2026 4:14 PM, Mukesh Savaliya wrote:
> On 11/3/2026 2:26 PM, Aniket Randive wrote:
> > I2C transfers in GPI DMA mode can fail with -EIO when a target holds
> > SDA low, leaving the bus stuck and preventing subsequent transactions.
> > The GPI completion callback reports a NACK and a genuine bus error
> > alike as -EIO, and the existing recovery path switches the SE to FIFO
> > mode which is not valid in GPI DMA mode.
> >
> > Add bus recovery support using the I2C_BUS_CLEAR and I2C_STOP_ON_BUS
> > opcodes issued via the GPI TX DMA channel. Guard the -EIO recovery
> > trigger with a SE_GENI_IOS I2C_BUS_FREE check to skip recovery when both
> > SDA and SCL are already released. Extend the recovery callback to 
> > dispatch
> > through the GPI DMA path when gi2c->gpi_mode is set.
> >
> > Use the adapter timeout for GPI recovery commands, and preserve the DMA
> > configuration error code when GPI setup fails.
> >
> > Stop recovery on a GPI command timeout and report DMA termination
> > failures. Do not issue another command or override the timeout with a
> > bus-idle result, since DMA cleanup may not have completed successfully.
> >
> > Signed-off-by: Aniket Randive <aniket.randive@xxxxxxxxxxxxxxxx>
> > ---
> >   drivers/i2c/busses/i2c-qcom-geni.c | 107 +++++++++++++++++++++++++++ 
> > +++++-----
> >   1 file changed, 94 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/ 
> > i2c-qcom-geni.c
>
> [...]
>
> > @@ -1356,10 +1439,8 @@ static int geni_i2c_probe(struct 
> > platform_device *pdev)
> >       if (ret < 0)
> >           return ret;
> > -    if (!gi2c->gpi_mode) {
> > -        gi2c->rinfo.recover_bus = geni_i2c_recover_bus;
> > -        gi2c->adap.bus_recovery_info = &gi2c->rinfo;
> > -    }
> > +    gi2c->rinfo.recover_bus = geni_i2c_recover_bus;
> > +    gi2c->adap.bus_recovery_info = &gi2c->rinfo;
>
> I guess one more time this. Why patch 2 is adding and patch 3 is 
> removing the change ? keep it clean way.

This is intentional. In patch 2, bus recovery is supported only in FIFO 
mode, so we guard the registration with !gi2c->gpi_mode. Patch 3 adds 
the corresponding bus recovery support for GPI mode, after which the 
mode check is no longer needed and is removed.

> >       ret = i2c_add_adapter(&gi2c->adap);
> >       if (ret) {