6.15-stable review patch. If anyone has any objections, please let me know.
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From: Lukasz Kucharczyk lukasz.kucharczyk@leica-geosystems.com
commit a5d0b9e32745277644cda8d7d334e7080bd339bf upstream.
Acknowledge the byte count submitted by the target. When I2C_SMBUS_BLOCK_DATA read operation is executed by i2c_smbus_xfer_emulated(), the length of the second (read) message is set to 1. Length of the block is supposed to be obtained from the target by the underlying bus driver. The i2c_imx_isr_read() function should emit the acknowledge on i2c bus after reading the first byte (i.e., byte count) while processing such message (as defined in Section 6.5.7 of System Management Bus Specification [1]). Without this acknowledge, the target does not submit subsequent bytes and the controller only reads 0xff's.
In addition, store the length of block data obtained from the target in the buffer provided by i2c_smbus_xfer_emulated() - otherwise the first byte of actual data is erroneously interpreted as length of the data block.
[1] https://smbus.org/specs/SMBus_3_3_20240512.pdf
Fixes: 5f5c2d4579ca ("i2c: imx: prevent rescheduling in non dma mode") Signed-off-by: Lukasz Kucharczyk lukasz.kucharczyk@leica-geosystems.com Cc: stable@vger.kernel.org # v6.13+ Acked-by: Oleksij Rempel o.rempel@pengutronix.de Reviewed-by: Stefan Eichenberger eichest@gmail.com Reviewed-by: Carlos Song carlos.song@nxp.com Signed-off-by: Andi Shyti andi.shyti@kernel.org Link: https://lore.kernel.org/r/20250520122252.1475403-1-lukasz.kucharczyk@leica-g... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/i2c/busses/i2c-imx.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index e5732b0557fb..205cc132fdec 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -1008,7 +1008,7 @@ static inline int i2c_imx_isr_read(struct imx_i2c_struct *i2c_imx) /* setup bus to read data */ temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); temp &= ~I2CR_MTX; - if (i2c_imx->msg->len - 1) + if ((i2c_imx->msg->len - 1) || (i2c_imx->msg->flags & I2C_M_RECV_LEN)) temp &= ~I2CR_TXAK;
imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); @@ -1063,6 +1063,7 @@ static inline void i2c_imx_isr_read_block_data_len(struct imx_i2c_struct *i2c_im wake_up(&i2c_imx->queue); } i2c_imx->msg->len += len; + i2c_imx->msg->buf[i2c_imx->msg_buf_idx++] = len; }
static irqreturn_t i2c_imx_master_isr(struct imx_i2c_struct *i2c_imx, unsigned int status)