Re: [PATCH v2 2/2] mfd: cros_ec: Read EC features during probe to catch transfer error

[Lee Jones]

On Thu, 18 Jun 2026, Tzung-Bi Shih wrote:

> On Thu, Jun 18, 2026 at 09:40:37AM +0100, Lee Jones wrote:
> > On Mon, 08 Jun 2026, Andrei Kuchynski wrote:
> > 
> > > cros_ec_check_features() does not return an error if the underlying
> > > EC_CMD_GET_FEATURES command fails. Consequently, when the Fingerprint
> > > device fails to respond, the probe function ignores the failure and falls
> > > back to installing it as 'cros_ec' device instead of 'cros_fp'.
> > > This leads to a sysfs duplicate filename collision later when the real
> > > 'cros_ec' device attempts to register:
> > > 
> > >   cros-ec-spi spi5.0: EC failed to respond in time
> > >   cros-ec-dev.19.auto: cannot get EC features: -110
> > >   sysfs : cannot create duplicate filename '/class/chromeos/cros_ec'
> > >         : sysfs_do_create_link_sd+0x94/0xdc
> > >         : ec_device_probe+0x150/0x4f0
> > > 
> > > Fix this by explicitly calling the newly introduced cros_ec_read_features()
> > > function. If the transfer fails, abort the broken device initialization.
> > > Move the initialization of class_dev before this call to prevent a missing
> > > release() callback warning on the error path.
> > > 
> > > Signed-off-by: Andrei Kuchynski <akuchynski@xxxxxxxxxxxx>
> > > ---
> > >  drivers/mfd/cros_ec_dev.c | 18 +++++++++++-------
> > >  1 file changed, 11 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> > > index 39430dd44e30c..a8c6300248d59 100644
> > > --- a/drivers/mfd/cros_ec_dev.c
> > > +++ b/drivers/mfd/cros_ec_dev.c
> > > @@ -203,6 +203,17 @@ static int ec_device_probe(struct platform_device *pdev)
> > >  	ec->features.flags[1] = -1U; /* Not cached yet */
> > >  	device_initialize(&ec->class_dev);
> > >  
> > > +	/*
> > > +	 * Add the class device
> > > +	 */
> > > +	ec->class_dev.class = &cros_class;
> > > +	ec->class_dev.parent = dev;
> > > +	ec->class_dev.release = cros_ec_class_release;
> > > +
> > > +	retval = cros_ec_read_features(ec);
> > 
> > This depends on the other patch.
> > 
> > Once it's been Reviewed / Acked, I'd be happy to take both and submit an IB.
> 
> FWIW: I gave my A-b tag in v1 and it has been carried to [PATCH v2 1/2]
> platform/chrome: cros_ec_proto: Introduce cros_ec_read_features helper.

I see it.  Thank you.

Note to self: Take the set after -rc1

-- 
Lee Jones