Currently, the driver will happily register the switch/mux devices, and so long as the i2c master doesn't complain, the user would never know there's something wrong. Add a device id check (based on [1]) and return -ENODEV if the read fails or returns nonsense. Checking the value on a Qualcomm SM6115P-based Lenovo Tab P11 tablet, the ID mentioned in the datasheet does indeed show up: fsa4480 1-0042: Found FSA4480 v1.1 (Vendor ID = 0) [1] https://www.onsemi.com/pdf/datasheet/fsa4480-d.pdf Fixes: 1dc246320c6b ("usb: typec: mux: Add On Semi fsa4480 driver") Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> --- drivers/usb/typec/mux/fsa4480.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/usb/typec/mux/fsa4480.c b/drivers/usb/typec/mux/fsa4480.c index cb7cdf90cb0a..d622f4f3bd54 100644 --- a/drivers/usb/typec/mux/fsa4480.c +++ b/drivers/usb/typec/mux/fsa4480.c @@ -13,6 +13,10 @@ #include <linux/usb/typec_dp.h> #include <linux/usb/typec_mux.h> +#define FSA4480_DEVICE_ID 0x00 + #define DEVICE_ID_VENDOR_ID GENMASK(7, 6) + #define DEVICE_ID_VERSION_ID GENMASK(5, 3) + #define DEVICE_ID_REV_ID GENMASK(2, 0) #define FSA4480_SWITCH_ENABLE 0x04 #define FSA4480_SWITCH_SELECT 0x05 #define FSA4480_SWITCH_STATUS1 0x07 @@ -251,6 +255,7 @@ static int fsa4480_probe(struct i2c_client *client) struct typec_switch_desc sw_desc = { }; struct typec_mux_desc mux_desc = { }; struct fsa4480 *fsa; + int val = 0; int ret; fsa = devm_kzalloc(dev, sizeof(*fsa), GFP_KERNEL); @@ -268,6 +273,15 @@ static int fsa4480_probe(struct i2c_client *client) if (IS_ERR(fsa->regmap)) return dev_err_probe(dev, PTR_ERR(fsa->regmap), "failed to initialize regmap\n"); + ret = regmap_read(fsa->regmap, FSA4480_DEVICE_ID, &val); + if (ret || !val) + return dev_err_probe(dev, -ENODEV, "FSA4480 not found\n"); + + dev_dbg(dev, "Found FSA4480 v%lu.%lu (Vendor ID = %lu)\n", + FIELD_GET(DEVICE_ID_VERSION_ID, val), + FIELD_GET(DEVICE_ID_REV_ID, val), + FIELD_GET(DEVICE_ID_VENDOR_ID, val)); + /* Safe mode */ fsa->cur_enable = FSA4480_ENABLE_DEVICE | FSA4480_ENABLE_USB; fsa->mode = TYPEC_STATE_SAFE; --- base-commit: ae00c445390b349e070a64dc62f08aa878db7248 change-id: 20240212-topic-fs4480_check-caa0160fb101 Best regards, -- Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
