6.12-stable review patch. If anyone has any objections, please let me know.
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From: Conor Dooley conor.dooley@microchip.com
commit 49e1f0fd0d4cb03a16b8526c4e683e1958f71490 upstream.
Running i2c-detect currently produces an output akin to: 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: 08 -- 0a -- 0c -- 0e -- 10: 10 -- 12 -- 14 -- 16 -- UU 19 -- 1b -- 1d -- 1f 20: -- 21 -- 23 -- 25 -- 27 -- 29 -- 2b -- 2d -- 2f 30: -- -- -- -- -- -- -- -- 38 -- 3a -- 3c -- 3e -- 40: 40 -- 42 -- 44 -- 46 -- 48 -- 4a -- 4c -- 4e -- 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: 60 -- 62 -- 64 -- 66 -- 68 -- 6a -- 6c -- 6e -- 70: 70 -- 72 -- 74 -- 76 --
This happens because for an i2c_msg with a len of 0 the driver will mark the transmission of the message as a success once the START has been sent, without waiting for the devices on the bus to respond with an ACK/NAK. Since i2cdetect seems to run in a tight loop over all addresses the NAK is treated as part of the next test for the next address.
Delete the fast path that marks a message as complete when idev->msg_len is zero after sending a START/RESTART since this isn't a valid scenario.
CC: stable@vger.kernel.org Fixes: 64a6f1c4987e ("i2c: add support for microchip fpga i2c controllers") Signed-off-by: Conor Dooley conor.dooley@microchip.com Reviewed-by: Andi Shyti andi.shyti@kernel.org Link: https://lore.kernel.org/r/20241218-outbid-encounter-b2e78b1cc707@spud Signed-off-by: Andi Shyti andi.shyti@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/i2c/busses/i2c-microchip-corei2c.c | 2 -- 1 file changed, 2 deletions(-)
--- a/drivers/i2c/busses/i2c-microchip-corei2c.c +++ b/drivers/i2c/busses/i2c-microchip-corei2c.c @@ -287,8 +287,6 @@ static irqreturn_t mchp_corei2c_handle_i ctrl &= ~CTRL_STA; writeb(idev->addr, idev->base + CORE_I2C_DATA); writeb(ctrl, idev->base + CORE_I2C_CTRL); - if (idev->msg_len == 0) - finished = true; break; case STATUS_M_ARB_LOST: idev->msg_err = -EAGAIN;