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authorPontus Andersson <epontan@gmail.com>2017-10-02 14:45:19 +0200
committerBen Hutchings <ben@decadent.org.uk>2017-11-11 13:34:04 +0000
commit88f33cee187088254441cb6a12b56d68dbd2d36e (patch)
treebdf02e2a381aed3b44c14f99ac72924cf7518607
parentf63a372e33e3dc51db6cc4dce13bfbd5db6817bf (diff)
i2c: ismt: Separate I2C block read from SMBus block read
commit c6ebcedbab7ca78984959386012a17b21183e1a3 upstream. Commit b6c159a9cb69 ("i2c: ismt: Don't duplicate the receive length for block reads") broke I2C block reads. It aimed to fix normal SMBus block read, but changed the correct behavior of I2C block read in the process. According to Documentation/i2c/smbus-protocol, one vital difference between normal SMBus block read and I2C block read is that there is no byte count prefixed in the data sent on the wire: SMBus Block Read: i2c_smbus_read_block_data() S Addr Wr [A] Comm [A] S Addr Rd [A] [Count] A [Data] A [Data] A ... A [Data] NA P I2C Block Read: i2c_smbus_read_i2c_block_data() S Addr Wr [A] Comm [A] S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P Therefore the two transaction types need to be processed differently in the driver by copying of the dma_buffer as done previously for the I2C_SMBUS_I2C_BLOCK_DATA case. Fixes: b6c159a9cb69 ("i2c: ismt: Don't duplicate the receive length for block reads") Signed-off-by: Pontus Andersson <epontan@gmail.com> Tested-by: Stephen Douthit <stephend@adiengineering.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r--drivers/i2c/busses/i2c-ismt.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/i2c/busses/i2c-ismt.c b/drivers/i2c/busses/i2c-ismt.c
index 1da38710f70c..51d62e0c1113 100644
--- a/drivers/i2c/busses/i2c-ismt.c
+++ b/drivers/i2c/busses/i2c-ismt.c
@@ -343,12 +343,15 @@ static int ismt_process_desc(const struct ismt_desc *desc,
data->word = dma_buffer[0] | (dma_buffer[1] << 8);
break;
case I2C_SMBUS_BLOCK_DATA:
- case I2C_SMBUS_I2C_BLOCK_DATA:
if (desc->rxbytes != dma_buffer[0] + 1)
return -EMSGSIZE;
memcpy(data->block, dma_buffer, desc->rxbytes);
break;
+ case I2C_SMBUS_I2C_BLOCK_DATA:
+ memcpy(&data->block[1], dma_buffer, desc->rxbytes);
+ data->block[0] = desc->rxbytes;
+ break;
}
return 0;
}