diff options
Diffstat (limited to 'drivers/hid/i2c-hid/i2c-hid-core.c')
| -rw-r--r-- | drivers/hid/i2c-hid/i2c-hid-core.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c index 2df1ab3c31cc..39ed58a8a04c 100644 --- a/drivers/hid/i2c-hid/i2c-hid-core.c +++ b/drivers/hid/i2c-hid/i2c-hid-core.c @@ -164,6 +164,24 @@ static u32 i2c_hid_lookup_quirk(const u16 idVendor, const u16 idProduct) return quirks; } +static int i2c_hid_probe_address(struct i2c_hid *ihid) +{ + int ret; + + /* + * Some STM-based devices need 400µs after a rising clock edge to wake + * from deep sleep, in which case the first read will fail. Try after a + * short sleep to see if the device came alive on the bus. Certain + * Weida Tech devices also need this. + */ + ret = i2c_smbus_read_byte(ihid->client); + if (ret < 0) { + usleep_range(400, 500); + ret = i2c_smbus_read_byte(ihid->client); + } + return ret < 0 ? ret : 0; +} + static int i2c_hid_xfer(struct i2c_hid *ihid, u8 *send_buf, int send_len, u8 *recv_buf, int recv_len) { @@ -1014,8 +1032,7 @@ static int __i2c_hid_core_probe(struct i2c_hid *ihid) struct hid_device *hid = ihid->hid; int ret; - /* Make sure there is something at this address */ - ret = i2c_smbus_read_byte(client); + ret = i2c_hid_probe_address(ihid); if (ret < 0) { i2c_hid_dbg(ihid, "nothing at this address: %d\n", ret); return -ENXIO; |