i2c: imx: fix missing stop condition in single-master mode

A regression was introduced with the implementation of single-master
mode, preventing proper stop conditions from being generated. Devices
that require a valid stop condition, such as EEPROMs, fail to function
correctly as a result.

The issue only affects devices with the single-master property enabled.

This commit resolves the issue by re-enabling I2C bus busy bit (IBB)
polling for single-master mode when generating a stop condition. The fix
further ensures that the i2c_imx->stopped flag is cleared at the start
of each transfer, allowing the stop condition to be correctly generated
in i2c_imx_stop().

According to the reference manual (IMX8MMRM, Rev. 2, 09/2019, page
5270), polling the IBB bit to determine if the bus is free is only
necessary in multi-master mode. Consequently, the IBB bit is not polled
for the start condition in single-master mode.

Fixes: 6692694aca86 ("i2c: imx: do not poll for bus busy in single master mode")
Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Link: https://lore.kernel.org/r/20241216151829.74056-1-eichest@gmail.com
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index f751d231ded87cf549bf14892421fc40c128bdf8..488ee351131450ca9eed6c3385ae49ecc4007161 100644 (file)
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -532,22 +532,20 @@ static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx)
 
 static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool atomic)
 {
+       bool multi_master = i2c_imx->multi_master;
        unsigned long orig_jiffies = jiffies;
        unsigned int temp;
 
-       if (!i2c_imx->multi_master)
-               return 0;
-
        while (1) {
                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
 
                /* check for arbitration lost */
-               if (temp & I2SR_IAL) {
+               if (multi_master && (temp & I2SR_IAL)) {
                        i2c_imx_clear_irq(i2c_imx, I2SR_IAL);
                        return -EAGAIN;
                }
 
-               if (for_busy && (temp & I2SR_IBB)) {
+               if (for_busy && (!multi_master || (temp & I2SR_IBB))) {
                        i2c_imx->stopped = 0;
                        break;
                }