diff mbox series

i2c: i801: Fix block process call transactions

Message ID 20240214155939.728155bc@endymion.delvare
State New
Headers show
Series i2c: i801: Fix block process call transactions | expand

Commit Message

Jean Delvare Feb. 14, 2024, 2:59 p.m. UTC 
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@suse.de>
Reported-by: Piotr Zakowski <piotr.zakowski@intel.com>
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(-)
diff mbox series

Patch

--- 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));
 	}