Compatibility with compiled Micropython

[shivampotdar]

I see that the prebuilt image in this repository is based on MicroPython v1.12-571 (some intermediate version I guess?)

I tried compiling micropython using GCC cross-compiler on Ubuntu 20.04 (with both buildroot download and gcc9.3 based from debian repositories) I attempted using the current master branch, v1.13 and v1.12 from the micropython repo. In all the cases, although I can compile without errors, when I run core_tb, I am not able to issue any inputs in the terminal from the keyboard. This does not happen with the prebuilt image.

I am not sure how exactly shall I debug this. But I would be happy to help and provide more details if neeeded.

Thank you.

[paulusmack]

This sounds like your image is trying to access the potato UART but core_tb has the 16550-style UART.

[titof49]

Hi @paulusmack Paul @antonblanchard , i had the same issue.

I saw that you can set the 16550-style UART. but from my previous tests it wasn't functionnal. i'll check it with the latest version of micropython .

[titof49]

[Solved]

@paulusmack @antonblanchard @shenki @mikey to correct the issue, you can change in the makefile :

UART ?= potato

by

UART ?= lpc_serial

after you can rebuild and recreate the link

enjoy again ;->>

below the full modifications:

titof49@pcdev:~/uwatt/micropython/ports/powerpc$ diff Makefile Makefile.old
10c10
< UART ?= lpc_serial
---
> UART ?= potato

[antonblanchard]

Thanks @titof49! We should update micropython to use the 16550 all the time, and eventually get rid of the potato UART in microwatt.

[iagocaran]

Instead of changing the makefile, you can compile like this:

make -j$(nproc) UART=lpc_serial

[167rgc911]

In the latest code this seems to be broken again:

(1) potato (default build of micropython):

rgc:~/i/microwatt$ ./core_tb > debug_log
MicroPython v1.19.1-782-g699477d12 on 2023-01-10; bare-metal with POWERPC
Type "help()" for more information.
>>>

• micropython seems to output the debug string properly
• but user is unable to perform any input

(2) UART (lpc_serial in micropython):

rgc:~/i/microwatt$ ./core_tb > debug_log

• micropython can't even output any debug string

AFAIK lpc_uart_init() is https://github.com/micropython/micropython/blob/1f371947309c5ea6023b6d9065415697cbc75578/ports/powerpc/uart_lpc_serial.c#L100

using a different base address now (LPC_UART_BASE). https://github.com/micropython/micropython/blob/1f371947309c5ea6023b6d9065415697cbc75578/ports/powerpc/uart_lpc_serial.c#L39

Edit # 1 It is an issue with micropython. Incorrect register offsets. So modifying uart_lpc_serial.c to something like below works.

diff --git a/ports/powerpc/uart_lpc_serial.c b/ports/powerpc/uart_lpc_serial.c
index 760615041..93a9af55f 100644
--- a/ports/powerpc/uart_lpc_serial.c
+++ b/ports/powerpc/uart_lpc_serial.c
@@ -36,21 +36,20 @@
 #define PROC_FREQ       50000000
 #define UART_FREQ       115200
 #define UART_BASE       0xc0002000
-#define LPC_UART_BASE   0x60300d00103f8
-
-/* Taken from skiboot */
-#define REG_RBR         0
-#define REG_THR         0
-#define REG_DLL         0
-#define REG_IER         1
-#define REG_DLM         1
-#define REG_FCR         2
-#define REG_IIR         2
-#define REG_LCR         3
-#define REG_MCR         4
-#define REG_LSR         5
-#define REG_MSR         6
-#define REG_SCR         7
+#define LPC_UART_BASE   UART_BASE
+
+#define REG_RBR         0x00
+#define REG_THR         0x00
+#define REG_DLL         0x00
+#define REG_IER         0x04
+#define REG_DLM         0x04
+#define REG_FCR         0x08
+#define REG_IIR         0x08
+#define REG_LCR         0x0c
+#define REG_MCR         0x10
+#define REG_LSR         0x14
+#define REG_MSR         0x18
+#define REG_SCR         0x1c

 #define LSR_DR          0x01  /* Data ready */
 #define LSR_OE          0x02  /* Overrun */

Both input and output works now for lpc_serial (UART=lpc_serial make) build of micropython.

rgc:~/i/microwatt$ ./core_tb > debug_log
MicroPython v1.19.1-782-g699477d12-dirty on 2023-01-10; bare-metal with POWERPC
Type "help()" for more information.
>>> 1+19
20
>>>

[titof49]

You must change uart mode see #246 issue on git mocrowattLe 10 janv. 2023 03:36, rgc @.***> a écrit : In the latest code this seems to be broken again: (1) potato (default build of micropython):

rgc:~/i/microwatt$ ./core_tb > debug_log MicroPython v1.19.1-782-g699477d12 on 2023-01-10; bare-metal with POWERPC Type "help()" for more information.

========== micropython seems to output the debug string properlybut user is unable to perform any input (2) UART (lpc_serial in micropython):

rgc:~/i/microwatt$ ./core_tb > debug_log

micropython can't even output any debug string AFAIK lpc_uart_init() is https://github.com/micropython/micropython/blob/1f371947309c5ea6023b6d9065415697cbc75578/ports/powerpc/uart_lpc_serial.c#L100 using a different base address now (LPC_UART_BASE). https://github.com/micropython/micropython/blob/1f371947309c5ea6023b6d9065415697cbc75578/ports/powerpc/uart_lpc_serial.c#L39

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