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| author |   Eudean Sun <eudean@arista.com> | 2017-11-21 10:43:24 -0800 |
|---|---|---|
| committer |   Jiri Kosina <jkosina@suse.cz> | 2017-11-21 21:39:45 +0100 |
| commit | 542134c0375b5ca2b1d18490c02b8a20bfdd8d74 (patch) | |
| tree | 5e00d617d6608e4914dcf7ac381b6e170ee0ca85 /drivers/hid | |
| parent | Merge branch 'for-linus' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jikos/hid (diff) | |
| download | linux-dev-542134c0375b5ca2b1d18490c02b8a20bfdd8d74.tar.xz linux-dev-542134c0375b5ca2b1d18490c02b8a20bfdd8d74.zip | |
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.c | 15 |
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; |