On Fri, Jun 10, 2016 at 2:55 PM, <[email protected]> wrote: > > Hello, > > I have an application that uses UART2. It runs fine under Debian 7 > ("Wheezy") however it doesn't under Debian 8 ("Jessie", kernel: > 4.1.15-ti-rt-r43); nothing arrives at the corresponding tty file > (/dev/ttyO2). > For enabling UARTs I declared > > cape_enable=capemgr.enable_partno=BB-UART2 (Debian 7) > > cape_enable=bone_capemgr.enable_partno=BB-UART2 (Debian 8) > > in /boot/uEnv.txt. > > (Note that when I use UART4 instead of UART2 my application runs fine under > both operating systems.) > > So I tried to figure out the changes from Debian 7 to Debian 8 by looking at > the dts files. Looking at cape-universal-00A0.dts revealed: > > Debian 7: > > /************************/ > /* UARTs */ > /************************/ > > fragment@10 { > target = <&uart2>; /* really uart1 */ > __overlay__ { > status = "okay"; > pinctrl-names = "default"; > pinctrl-0 = <>; > }; > }; > > fragment@11 { > target = <&uart3>; /* really uart2 */ > __overlay__ { > status = "okay"; > pinctrl-names = "default"; > pinctrl-0 = <>; > }; > }; > > Debian 8 (/opt/source/bb.org-overlays/src/arm/cape-universal-00A0.dts): > > /************************/ > /* UARTs */ > /************************/ > > fragment@10 { > target = <&uart2>; /* really uart1 */ > __overlay__ { > status = "okay"; > pinctrl-names = "default"; > pinctrl-0 = <>; > }; > }; > > fragment@11 { > target = <&uart3>; /* really uart2 */ > __overlay__ { > status = "okay"; > pinctrl-names = "default"; > pinctrl-0 = <>; > }; > }; > > Debian 8 (/opt/source/bb.org-overlays/src/arm/cape-universal-00A0.dts): > > /************************/ > /* UARTs */ > /************************/ > > fragment@10 { > target = <&uart1>; > __overlay__ { > status = "okay"; > pinctrl-names = "default"; > pinctrl-0 = <>; > }; > }; > > fragment@11 { > target = <&uart2>; > __overlay__ { > status = "okay"; > pinctrl-names = "default"; > pinctrl-0 = <>; > }; > }; > > I don't know what this exactly means, especially the "really uart<x>". Can > anyone clarify here? Also there are two different cape-universal-00A0.dts > files under Debian 8, which one is relevant? I see that in /boot/uEnv.txt > the following line is enabled by default: cmdline=coherent_pool=1M quiet > cape_universal=enable. Which dts (dtb) file does it refer to? > > Comparing /opt/source/bb.org-overlays/src/arm/BB-UART4-00A0.dts and > /opt/source/bb.org-overlays/src/arm/BB-UART2-00A0.dts under Debian 8 > revealed that apparently both pins have a different multiplexer mode (uart2 > -> MUX_MODE1, uart4 -> MUX_MODE6). Does this have any effect? I couldn't > find an equivalent dts file for Debian 7. > Probably related: from cape-universal-00A0.dts I see > > UART2 (P9_21, P9_22): > > [...] > P9_21_uart_pin: pinmux_P9_21_uart_pin { > pinctrl-single,pins = <0x154 0x31>; }; /* Mode 1, > Pull-Up, RxActive */ > > [...] > P9_22_uart_pin: pinmux_P9_22_uart_pin { > pinctrl-single,pins = <0x150 0x31>; }; /* Mode 1, > Pull-Up, RxActive */ > > UART4 (P9_11, P9_13): > > [...] > P9_11_uart_pin: pinmux_P9_11_uart_pin { > pinctrl-single,pins = <0x070 0x36>; }; /* Mode 6, > Pull-Up, RxActive */ > > [...] > P9_13_uart_pin: pinmux_P9_13_uart_pin { > pinctrl-single,pins = <0x074 0x36>; }; /* Mode 6, > Pull-Up, RxActive */ > > Is this relevant / exhibiting different behavior? > > I also realized that for UART2 there is an additional dts file under Debian > 8: /opt/source/bb.org-overlays/src/arm/BB-UART2-RTSCTS-00A0.dts > For UART4 there is no equivalent. How is this related? > > The pin multiplexing declarations in cape-universal-00A0.dts (P9_21_pinmux, > P9_22_pinmux) seem to remain the same when going from Debian 7 to Debian 8. > > So does anyone know the reason why UART2 behaves differently on Debian 8 > (compared to Debian 7)?
3.8.13: wrong usart # (off by one..) 3.14.x -> 4.1.x -> 4.4.x -> mainline: correct usart # Regards, -- Robert Nelson https://rcn-ee.com/ -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAOCHtYivR4qq-aM-zXT8RirJLEzkBFHEchpGy7x1X%3DMrnAogqQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
