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

[Tzung-Bi Shih <tzungbi@kernel.org>]

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@chromium.org>
> > ---
> >  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.