[PATCH v2] usb: misc: ljca: Fix enumeration error on Dell Latitude 9420

From: Hans de Goede <hdegoede@redhat.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andi Shyti <andi.shyti@linux.intel.com>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Wentong Wu <wentong.wu@intel.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
	Oliver Neukum <oneukum@suse.com>,
	linux-usb@vger.kernel.org, stable@vger.kernel.org
Subject: [PATCH v2] usb: misc: ljca: Fix enumeration error on Dell Latitude 9420
Date: Sat,  4 Nov 2023 18:51:04 +0100	[thread overview]
Message-ID: <20231104175104.38786-1-hdegoede@redhat.com> (raw)

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: 54f225fa5b58 ("usb: Add support for Intel LJCA device")
Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v2:
- Small commit msg + comment fixes
- Add Fixes tag + Cc: stable
---
 drivers/usb/misc/usb-ljca.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/misc/usb-ljca.c b/drivers/usb/misc/usb-ljca.c
index c9decd0396d4..a280d3a54b18 100644
--- a/drivers/usb/misc/usb-ljca.c
+++ b/drivers/usb/misc/usb-ljca.c
@@ -656,10 +656,11 @@ 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;
-- 
2.41.0

