RTEMS booting problem for PICO-PI-IMX7 board.

[Russell Haley]

On Mon, Apr 9, 2018 at 6:50 PM, JunBeom Kim (EmbedCoreTech) <
jbkim at e-coretech.kr> wrote:

> Dear Sir,
>
> Is there RTEMS users for running RTEMS for PICO-PI-IMX7 board ?
>
> I purchased PICO-PI-IMX7 from Wanboard.
> https://www.wandboard.org/products/android-things/PICO-PI-IMX7/
>
> I am tring to test RTEMS on PICO-PI-IMX7 using RTEMS current version for
> i.MX7D SDB board.
>

Ooooh, this is a sexy little kit...

https://www.variscite.com/products/system-on-module-som/cortex-a7/var-som-mx7-nxp-freescale-imx-7/


>
> On referencing, when I check PICO-PI-IMX7 board, there is u-boot only.
> Also, there is eMMC memory only. (It was headache in first)
> Therefore, I needed additional work for writing your modified u-boot
> and/or for preparing RTEMS image FAT32 storage. Additional work means that
> u-boot writing by dd command and eMMC partition configuration by fdisk
> command after Linux kernel is booting.
>
> At this time, I removed Linux kernel image on eMMC storage and I am ready
> to test RTEMS image only.
> Also, If user use "ums 0 mmc 0" command in u-boot, user can replace RTEMS
> image and dtb file easily on PC(Windows or Linux Desktop).
>
> As I check difference between PICO-PI-IMX7 and i.MX7D SDB, UART debug port
> number is different.
>  - PICO-PI-IMX7 : UART5 (serial4)
>  - i.MX7D SDB : UART1 (serial0)
>
> After I check current RTEMS bsp source, I modified console-config.c due to
> UART port number change in below;
>
> < Original code : for UART1 debug port >
> static imx_uart_context imx_uart_instances[7];
> static imx_uart_context *imx_uart_console = &imx_uart_instances[0];
>
> < Modified code : for UART5 debug port >
> static imx_uart_context imx_uart_instances[7];
> static imx_uart_context *imx_uart_console = &imx_uart_instances[4];
>
> Even though I modified this, there is not any output after running RTEMS.
>
> I am checking UART configuration by FDT.
>
> As I check imx_uart_probe() function of console-config.c, there is
> "chosen" and "stdout-path" keyword in below;
>
> static void imx_uart_probe(void)
> {
>   const void *fdt;
>   int node;
>   int offset;
>   const char *console;
>   size_t i;
>
>   fdt = bsp_fdt_get();
>   node = fdt_path_offset(fdt, "/chosen");
>
>   console = fdt_getprop(fdt, node, "stdout-path", NULL);
>   if (console == NULL) {
>     console = "";
>   }
>   ...
> }
>
> I think that there should be declaration for "stdout-path" of "chosen"
> area in dts(including dtsi) source file.
>
> As I check dts files on lastest Linux kernel for both i.MX7D SDB and
> PICO-IMX7, there is not "stdout-path" information of "chosen".
>
> I attached files related with this.
>
>  - i.MX7D SDB : imx7d-sdb.dts with imx7d.dtsi, imx7s.dtsi
>  - PICO-IMX7 : imx7d-pico-pi.dts with imx7d-pico.dtsi, imx7d.dtsi,
> imx7s.dtsi
>
> Because there is blank information for "chosen" in imx7s.dtsi, I added
> "stdout-path" in imx7d-pico-dtsi.
>
> < imx7s.dtsi >
> / {
>         #address-cells = <1>;
>         #size-cells = <1>;
>         /*
>          * The decompressor and also some bootloaders rely on a
>          * pre-existing /chosen node to be available to insert the
>          * command line and merge other ATAGS info.
>          * Also for U-Boot there must be a pre-existing /memory node.
>          */
>         chosen {}; ==> "there is not any information for stdout-path"
>         memory { device_type = "memory"; };
>   ...
> }
>
> < My modified imx7d-pico.dtsi >
>
> / {
>         model = "Technexion Pico i.MX7D Board";
>         compatible = "technexion,imx7d-pico", "fsl,imx7d";
>
>         memory at 80000000 {
>                 reg = <0x80000000 0x80000000>;
>         };
>
>         chosen {
>                 stdout-path = &uart5"; ==> "I added stdout-path
> information".
>         };
>
>   ...
> }
>
> After I modified imx7d-pico.dtsi, I made imx7d-pico-pi.dtb.
>
> Finally, I tried to run RTEMS using the revised dtb file. But, there is
> not any serial output.
>
> On referencing, there is not JTAG debug port in PICO board, It is very
> difficult to debug current RTEMS for i.MX7D.
>
> If there is mistake in my trial step, please let me know that.
>
> Best Regards,
> JunBeom Kim
> ~~~~~~~~~~~~~~~~~~~~~~
> President / EmbedCoreTech
> Phone: +82-31-396-5584
> Fax: +82-504-065-5720
> Mobile:+82-10-6425-5720
> Email: jbkim at e-coretech.kr
> Web: www.e-coretech.kr
> ~~~~~~~~~~~~~~~~~~~~~~
>
>
>
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