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authorEudean Sun <eudean@arista.com>2017-11-21 10:43:24 -0800
committerJiri Kosina <jkosina@suse.cz>2017-11-21 21:39:45 +0100
commit542134c0375b5ca2b1d18490c02b8a20bfdd8d74 (patch)
tree5e00d617d6608e4914dcf7ac381b6e170ee0ca85 /drivers/hid
parent20df15783a44a289aaa8c8f83b3f715f9040c9c2 (diff)
HID: cp2112: Fix I2C_BLOCK_DATA transactions
The existing driver erroneously treats I2C_BLOCK_DATA and BLOCK_DATA commands the same. For I2C_BLOCK_DATA reads, the length of the read is provided in data->block[0], but the length itself should not be sent to the slave. In contrast, for BLOCK_DATA reads no length is specified since the length will be the first byte returned from the slave. When copying data back to the data buffer, for an I2C_BLOCK_DATA read we have to take care not to overwrite data->block[0] to avoid overwriting the length. A BLOCK_DATA read doesn't have this concern since the first byte returned by the device is the length and belongs in data->block[0]. For I2C_BLOCK_DATA writes, the length is also provided in data->block[0], but the length itself is not sent to the slave (in contrast to BLOCK_DATA writes where the length prefixes the data sent to the slave). This was tested on physical hardware using i2cdump with the i and s flags to test the behavior of I2C_BLOCK_DATA reads and BLOCK_DATA reads, respectively. Writes were not tested but the I2C_BLOCK_DATA write change is pretty simple to verify by inspection. Signed-off-by: Eudean Sun <eudean@arista.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid')
-rw-r--r--drivers/hid/hid-cp2112.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
index 68cdc962265b..271f31461da4 100644
--- a/drivers/hid/hid-cp2112.c
+++ b/drivers/hid/hid-cp2112.c
@@ -696,8 +696,16 @@ static int cp2112_xfer(struct i2c_adapter *adap, u16 addr,
(u8 *)&word, 2);
break;
case I2C_SMBUS_I2C_BLOCK_DATA:
- size = I2C_SMBUS_BLOCK_DATA;
- /* fallthrough */
+ if (read_write == I2C_SMBUS_READ) {
+ read_length = data->block[0];
+ count = cp2112_write_read_req(buf, addr, read_length,
+ command, NULL, 0);
+ } else {
+ count = cp2112_write_req(buf, addr, command,
+ data->block + 1,
+ data->block[0]);
+ }
+ break;
case I2C_SMBUS_BLOCK_DATA:
if (I2C_SMBUS_READ == read_write) {
count = cp2112_write_read_req(buf, addr,
@@ -785,6 +793,9 @@ static int cp2112_xfer(struct i2c_adapter *adap, u16 addr,
case I2C_SMBUS_WORD_DATA:
data->word = le16_to_cpup((__le16 *)buf);
break;
+ case I2C_SMBUS_I2C_BLOCK_DATA:
+ memcpy(data->block + 1, buf, read_length);
+ break;
case I2C_SMBUS_BLOCK_DATA:
if (read_length > I2C_SMBUS_BLOCK_MAX) {
ret = -EPROTO;

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