According to the Intel datasheets, software must reset the block buffer index twice for block process call transactions: once before writing the outgoing data to the buffer, and once again before reading the incoming data from the buffer. The driver is currently missing the second reset, causing the wrong portion of the block buffer to be read. Signed-off-by: Jean Delvare <jdelvare@xxxxxxx> Reported-by: Piotr Zakowski <piotr.zakowski@xxxxxxxxx> Closes: https://lore.kernel.org/linux-i2c/20240213120553.7b0ab120@endymion.delvare/ Fixes: 315cd67c9453 ("i2c: i801: Add Block Write-Block Read Process Call support") --- Piotr, does this change make your tests succeed? Alexander, I don't suppose you still have access to the hardware on which you were using block process call transactions back in 2019, but maybe you remember having to do the same change to make it work? drivers/i2c/busses/i2c-i801.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- linux-6.6.orig/drivers/i2c/busses/i2c-i801.c +++ linux-6.6/drivers/i2c/busses/i2c-i801.c @@ -500,11 +500,10 @@ static int i801_block_transaction_by_blo /* Set block buffer mode */ outb_p(inb_p(SMBAUXCTL(priv)) | SMBAUXCTL_E32B, SMBAUXCTL(priv)); - inb_p(SMBHSTCNT(priv)); /* reset the data buffer index */ - if (read_write == I2C_SMBUS_WRITE) { len = data->block[0]; outb_p(len, SMBHSTDAT0(priv)); + inb_p(SMBHSTCNT(priv)); /* reset the data buffer index */ for (i = 0; i < len; i++) outb_p(data->block[i+1], SMBBLKDAT(priv)); } @@ -522,6 +521,7 @@ static int i801_block_transaction_by_blo } data->block[0] = len; + inb_p(SMBHSTCNT(priv)); /* reset the data buffer index */ for (i = 0; i < len; i++) data->block[i + 1] = inb_p(SMBBLKDAT(priv)); } -- Jean Delvare SUSE L3 Support
