Flaky UART4 (ttymxc3) [ANSWERED]

[Oren.R]

Ian,
we'll take a look an advise, should be no issue

[Eran.M]

Hi Ian.
This is what I've done, and I have no issue:

Code: Select all

diff --git a/arch/arm/boot/dts/imx6ul-var-dart.dtsi b/arch/arm/boot/dts/imx6ul-var-dart.dtsi
index 0e82aad..cec3398 100755
--- a/arch/arm/boot/dts/imx6ul-var-dart.dtsi
+++ b/arch/arm/boot/dts/imx6ul-var-dart.dtsi
@@ -221,7 +221,7 @@
        pinctrl-0 = <&pinctrl_lcdif_dat
                     &pinctrl_lcdif_ctrl>;
        display = <&display0>;
-       status = "okay";
+       status = "disabled";
 
        display0: display {
                bits-per-pixel = <16>;
@@ -306,6 +306,13 @@
        status = "okay";
 };
 
+/* ttymxc3 UART */
+&uart4 {
+       pinctrl-names = "default";
+       pinctrl-0 = <&pinctrl_uart4>;
+       status = "okay";
+};
+
        /* dr_mode: One of "host", "peripheral" or "otg". Defaults to "otg" */
 &usbotg1 {
        dr_mode = "host";
@@ -574,6 +581,13 @@
                        >;
                };
 
+               pinctrl_uart4: uart4grp {
+                       fsl,pins = <
+                               MX6UL_PAD_LCD_CLK__UART4_DCE_TX      0x1b0b1
+                               MX6UL_PAD_LCD_ENABLE__UART4_DCE_RX   0x1b0b1
+                       >;
+               };
+
                pinctrl_usdhc1: usdhc1grp {
                        fsl,pins = <
                                MX6UL_PAD_SD1_CMD__USDHC1_CMD     0x17059


From what you describe, you probably have the same pads defined differently somewhere else (by default they are defined in pinctrl_lcdif_ctrl under lcdif, so you can see I've disabled it).
When you put the pin definitions under hog, they are being hogged first, and then the other definition is not taken.

[Eran.M]

Are you using our VAR-6ULCustomBoard, or your own board?
Can you try using our device tree with my patch just to check if you still have problems with the UART?
Did you verify that you do not use the same pads differently elsewhere?
If you want, you can send your custom device tree files, and I'll take a look. You can fill-out a support ticket at http://www.variscite.com/support/varisc ... mer-portal, and attach your files.