usb: misc: ljca: Fix enumeration error on Dell Latitude 9420

Not all LJCA chips implement SPI and on chips without SPI reading
the SPI descriptors will timeout.

On laptop models like the Dell Latitude 9420, this is expected behavior
and not an error.

Modify the driver to continue without instantiating a SPI auxbus child,
instead of failing to probe() the whole LJCA chip.

Fixes: acd6199f195d ("usb: Add support for Intel LJCA device")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Wentong Wu <wentong.wu@intel.com>
Link: https://lore.kernel.org/r/20231104175104.38786-1-hdegoede@redhat.com
Link: https://lore.kernel.org/r/20231121203205.223047-1-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/misc/usb-ljca.c b/drivers/usb/misc/usb-ljca.c
index 7f0deeb..35770e6 100644 (file)
--- a/drivers/usb/misc/usb-ljca.c
+++ b/drivers/usb/misc/usb-ljca.c
@@ -646,10 +646,11 @@ static int ljca_enumerate_spi(struct ljca_adapter *adap)
        unsigned int i;
        int ret;
 
+       /* Not all LJCA chips implement SPI, a timeout reading the descriptors is normal */
        ret = ljca_send(adap, LJCA_CLIENT_MNG, LJCA_MNG_ENUM_SPI, NULL, 0, buf,
                        sizeof(buf), true, LJCA_ENUM_CLIENT_TIMEOUT_MS);
        if (ret < 0)
-               return ret;
+               return (ret == -ETIMEDOUT) ? 0 : ret;
 
        /* check firmware response */
        desc = (struct ljca_spi_descriptor *)buf;