On Thu, Jul 26, 2018 at 12:23 PM, Oleksij Rempel
[off-list ref] wrote:

.....

+
+/* Control Register */
+#define IMX_MU_xCR             0x24
+/* Transmit Interrupt Enable */
+#define IMX_MU_xCR_TIEn(x)     BIT(20 + (3 - (x)))
+/* Receive Interrupt Enable */
+#define IMX_MU_xCR_RIEn(x)     BIT(24 + (3 - (x)))
+
+#define IMX_MU_CHANS   4u
+

The 'u' unnecessarily refreshes my knowledge of C  :)

+struct imx_mu_con_priv {
+       int                     irq;
+       unsigned int            idx;
+       char                    *irq_desc;

Having      char  irq_desc[16];    seems simpler than free/kfree upon
each startup/shutdown. Simply use snprintf() in probe().

The rest of the driver seems fine.

Cheers!