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| author | Abdurrahman Hussain <abdurrahman@nexthop.ai> | 2026-09-24 17:10:37 -0700 |
|---|---|---|
| committer | Andi Shyti <andi.shyti@kernel.org> | 2026-09-28 01:28:42 +0200 |
| commit | 840d8acc87925deb3c75566fde9ca81d2f47f98c (patch) | |
| tree | d64377954d3366ecd1d329b117e6cc6a3faa9ae1 /drivers | |
| parent | e6fe3ea04f0113fe4d47c03d76e03805a4768ca7 (diff) | |
| download | linux-stable-840d8acc87925deb3c75566fde9ca81d2f47f98c.tar.gz linux-stable-840d8acc87925deb3c75566fde9ca81d2f47f98c.zip | |
i2c: xiic: don't clobber msg->len to signal block-read completion
At the end of a SMBus block read the BNB handler force-set
tx_msg->len = 1 to push xiic_tx_space() to zero so the STATE_DONE
branch would fire. Two problems:
1. tx_msg and rx_msg alias the same i2c_msg struct during a receive
(see xiic_start_recv), so overwriting tx_msg->len also changes
rx_msg->len. The i2c core's i2c_smbus_check_pec() then reads the
PEC from the wrong offset -- buf[0] instead of buf[rxmsg_len + 1]
-- and either mis-validates or returns -EBADMSG.
2. xiic_start_recv sets tx_pos = msg->len (typically 2 when PEC is
enabled). xiic_tx_space() is unsigned msg->len - tx_pos, so
setting msg->len = 1 with tx_pos = 2 underflows to 0xFFFFFFFF and
xiic_tx_space() never compares equal to 0 -- the STATE_DONE check
falls through to STATE_ERROR, giving -EIO.
Instead, advance tx_pos up to msg->len. That drives tx_space to 0
without touching msg->len, preserving the buffer length that
xiic_smbus_block_read_setup() already grew to cover the length byte,
the payload and the optional PEC byte.
Fixes: e4c1ff772e1a ("i2c: xiic: Add smbus_block_read functionality")
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Cc: <stable@vger.kernel.org> # v6.3+
Acked-by: Michal Simek <michal.simek@amd.com>
Reviewed-by: Shubhrajyoti Datta <shubhrajyoti.datta@amd.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://patch.msgid.link/20260924-i2c-xiic-v7-3-df7e752332ef@nexthop.ai
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/i2c/busses/i2c-xiic.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c index 5cd737c76..5e397a7e6 100644 --- a/drivers/i2c/busses/i2c-xiic.c +++ b/drivers/i2c/busses/i2c-xiic.c @@ -889,8 +889,11 @@ static irqreturn_t xiic_process(int irq, void *dev_id) if (i2c->tx_msg && i2c->smbus_block_read) { i2c->smbus_block_read = false; - /* Set requested message len=1 to indicate STATE_DONE */ - i2c->tx_msg->len = 1; + /* + * Drive xiic_tx_space() to 0 to signal STATE_DONE + * without truncating the rx_msg length. + */ + i2c->tx_pos = i2c->tx_msg->len; } if (!i2c->tx_msg) |