The device cp2112 does not support i2c combined transactions,
since unable to suppress the stop bit between adjacent i2c
transactions.
For this reason, in commit b9029345ed6483fcadadc4834b44a5656dd56d70
("HID: cp2112: add I2C mode") I have omitted the support for
num > 1 in i2c_transfer().But: 1) in few kernel drivers i2c_transfer() has been used to simplify the code by replacing a sequence of i2c_master_send() and i2c_master_recv(), e.g. in i2c-hid.c and iio subsystem. Those drivers will fail if used with current cp2112 driver. 2) in drivers/i2c/busses/ there are already drivers that implement i2c_transfer() as a sequence of elementary (not combined) i2c transactions, e.g. i2c-bcm2835.c, i2c-puv3.c, i2c-qup.c, i2c-robotfuzz-osif.c, i2c-viperboard.c, i2c-xlr.c. To fix 1) and considering 2), rewrite i2c_transfer() in case of num > 1 as a loop of non-combined i2c transactions. Signed-off-by: Antonio Borneo <borneo.anto...@gmail.com> --- Hi Benjamin, In [1] we had a talk about implementing i2c_transfer() as a sequence of elementary (not combined) i2c transactions. After Jonathan's reply in [2], I went to check better the existing I2C drivers and I changed opinion. Added linux-i2c list in copy to get feedback, if any, from the I2C experts. Regards, Antonio Borneo [1] https://lkml.org/lkml/2014/6/29/6 [2] https://lkml.org/lkml/2014/7/15/104 drivers/hid/hid-cp2112.c | 76 ++++++++++++++++++++++++------------------------ 1 file changed, 38 insertions(+), 38 deletions(-) diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c index 3318de6..76cad81 100644 --- a/drivers/hid/hid-cp2112.c +++ b/drivers/hid/hid-cp2112.c @@ -444,8 +444,7 @@ static int cp2112_i2c_write_req(void *buf, u8 slave_address, u8 *data, return data_length + 3; } -static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, - int num) +static int cp2112_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg) { struct cp2112_device *dev = (struct cp2112_device *)adap->algo_data; struct hid_device *hdev = dev->hdev; @@ -454,33 +453,18 @@ static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, unsigned int retries; int ret; - hid_dbg(hdev, "I2C %d messages\n", num); - - if (num != 1) { - hid_err(hdev, - "Multi-message I2C transactions not supported\n"); - return -EOPNOTSUPP; - } - - if (msgs->flags & I2C_M_RD) - count = cp2112_read_req(buf, msgs->addr, msgs->len); + if (msg->flags & I2C_M_RD) + count = cp2112_read_req(buf, msg->addr, msg->len); else - count = cp2112_i2c_write_req(buf, msgs->addr, msgs->buf, - msgs->len); - + count = cp2112_i2c_write_req(buf, msg->addr, msg->buf, + msg->len); if (count < 0) return count; - ret = hid_hw_power(hdev, PM_HINT_FULLON); - if (ret < 0) { - hid_err(hdev, "power management error: %d\n", ret); - return ret; - } - ret = cp2112_hid_output(hdev, buf, count, HID_OUTPUT_REPORT); if (ret < 0) { hid_warn(hdev, "Error starting transaction: %d\n", ret); - goto power_normal; + return ret; } for (retries = 0; retries < XFER_STATUS_RETRIES; ++retries) { @@ -488,7 +472,7 @@ static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, if (-EBUSY == ret) continue; if (ret < 0) - goto power_normal; + return ret; break; } @@ -502,30 +486,46 @@ static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, hid_warn(hdev, "Error cancelling transaction: %d\n", ret); - ret = -ETIMEDOUT; - goto power_normal; + return -ETIMEDOUT; } - if (!(msgs->flags & I2C_M_RD)) - goto finish; + if (!(msg->flags & I2C_M_RD)) + return 0; - ret = cp2112_read(dev, msgs->buf, msgs->len); + ret = cp2112_read(dev, msg->buf, msg->len); if (ret < 0) - goto power_normal; - if (ret != msgs->len) { - hid_warn(hdev, "short read: %d < %d\n", ret, msgs->len); - ret = -EIO; - goto power_normal; + return ret; + if (ret != msg->len) { + hid_warn(hdev, "short read: %d < %d\n", ret, msg->len); + return -EIO; } + return 0; +} -finish: - /* return the number of transferred messages */ - ret = 1; +static int cp2112_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, + int num) +{ + struct cp2112_device *dev = (struct cp2112_device *)adap->algo_data; + struct hid_device *hdev = dev->hdev; + int i, ret; + + hid_dbg(hdev, "I2C %d messages\n", num); + + ret = hid_hw_power(hdev, PM_HINT_FULLON); + if (ret < 0) { + hid_err(hdev, "power management error: %d\n", ret); + return ret; + } + + for (i = 0; i < num; i++) { + ret = cp2112_i2c_xfer_msg(adap, &msgs[i]); + if (ret < 0) + break; + } -power_normal: hid_hw_power(hdev, PM_HINT_NORMAL); hid_dbg(hdev, "I2C transfer finished: %d\n", ret); - return ret; + return (ret < 0) ? ret : num; } static int cp2112_xfer(struct i2c_adapter *adap, u16 addr, -- 2.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
