topic Re: SDRAM usage and data corruption in i.MX RT Crossover MCUs

SDRAM usage and data corruption

mspenard603 — Wed, 08 Jun 2022 20:02:12 GMT

Hi Gents,

I'm trying to use the starting region of SDRAM (it runs from 0x81000000 to 0x82000000). And I use XiP flash so application code does not run out of SDRAM. Heap is located at the end of SDRAM. My config is as seen below.

My issue is that I experience data going corrupt if I use space below 0x81000000 (e.g., at 0x80800000). Based on my config would one expect memory overlap corruption issues???

Re: SDRAM usage and data corruption

mspenard603 — Wed, 08 Jun 2022 20:23:03 GMT

My board.c lists two regions with the same base address (as used by SDRAM). Region 8 is what I expected. But why is there a Region1 specified at the same address???

/* Region 1 setting: Memory with Device type, not shareable, non-cacheable. */
MPU->RBAR = ARM_MPU_RBAR(1, 0x80000000U);
MPU->RASR = ARM_MPU_RASR(0, ARM_MPU_AP_FULL, 2, 0, 0, 0, 0, ARM_MPU_REGION_SIZE_1GB);

/* Region 8 setting: Memory with Normal type, not shareable, outer/inner write back */
MPU->RBAR = ARM_MPU_RBAR(8, 0x80000000U);
MPU->RASR = ARM_MPU_RASR(0, ARM_MPU_AP_FULL, 0, 0, 1, 1, 0, ARM_MPU_REGION_SIZE_32MB);

Re: SDRAM usage and data corruption

jeremyzhou — Thu, 09 Jun 2022 01:35:54 GMT

Hi,
Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
1) My issue is that I experience data going corrupt if I use space below 0x81000000 (e.g., at 0x80800000). Based on my config would one expect memory overlap corruption issues???
-- No, I don't think so.
2) But why is there a Region1 specified at the same address???
-- The newest configuration will the affect region finally, and the region 1 setting is used to set the attribute of the memories that are not targeted for any specific purposes, to assure their attaribute is certain.
Have a great day,
TIC

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Re: SDRAM usage and data corruption

jeremyzhou — Fri, 10 Jun 2022 03:01:12 GMT

Hi，
Thanks for your reply.
I think you'd better tell me what exactly LWIP demo you want to discuss.
Have a great day,
TIC

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Re: SDRAM usage and data corruption

mspenard603 — Fri, 10 Jun 2022 19:29:48 GMT

Well, my issue is related to LWIP across any of the demos...

From mem.c, this specifies LWIP heap usage. And I can move to SDRAM (0x8xxxxxxxx) if needed to free up SRAM_DTC:

#ifndef LWIP_RAM_HEAP_POINTER
/** the heap. we need one struct mem at the end and some room for alignment */
LWIP_DECLARE_MEMORY_ALIGNED(ram_heap, MEM_SIZE_ALIGNED + (2U * SIZEOF_STRUCT_MEM));

#define LWIP_RAM_HEAP_POINTER ram_heap

But I still see LWIP allocating a lot of stack when I examine the image. How do I move memp_memory_PBUF_POOL_base ?

Re: SDRAM usage and data corruption

jeremyzhou — Mon, 13 Jun 2022 09:45:49 GMT

Hi,
Thanks for your reply.
For instance, you can move the memp_memory_PBUF_POOL_base object to the SDRAM after the below configuration.

Have a great day,
TIC

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Re: SDRAM usage and data corruption

mspenard603 — Mon, 13 Jun 2022 13:07:09 GMT

In the linker script configuration? Sorry, haven't done much memory map config in here yet. So I need a bit more guidance.

Re: SDRAM usage and data corruption

mspenard603 — Mon, 13 Jun 2022 13:27:44 GMT

Is there something I can change in memp_std.h to move PBUF_POOL?

/*
* A list of pools of pbuf's used by LWIP.
*
* LWIP_PBUF_MEMPOOL(pool_name, number_elements, pbuf_payload_size, pool_description)
* creates a pool name MEMP_pool_name. description is used in stats.c
* This allocates enough space for the pbuf struct and a payload.
* (Example: pbuf_payload_size=0 allocates only size for the struct)
*/
LWIP_MEMPOOL(PBUF, MEMP_NUM_PBUF, sizeof(struct pbuf), "PBUF_REF/ROM")
LWIP_PBUF_MEMPOOL(PBUF_POOL, PBUF_POOL_SIZE, PBUF_POOL_BUFSIZE, "PBUF_POOL")

Re: SDRAM usage and data corruption

mspenard603 — Mon, 13 Jun 2022 15:14:26 GMT

The macros for this really telescope... trying to follow them down. I see this comment below. Should I be doing this? The NXP port of LWIP doesn't seem to have cc.h ...???

/**
* @ingroup mempool
* Declare a private memory pool
* Private mempools example:
* .h: only when pool is used in multiple .c files: LWIP_MEMPOOL_PROTOTYPE(my_private_pool);
* .c:
* - in global variables section: LWIP_MEMPOOL_DECLARE(my_private_pool, 10, sizeof(foo), "Some description")
* - call ONCE before using pool (e.g. in some init() function): LWIP_MEMPOOL_INIT(my_private_pool);
* - allocate: void* my_new_mem = LWIP_MEMPOOL_ALLOC(my_private_pool);
* - free: LWIP_MEMPOOL_FREE(my_private_pool, my_new_mem);
*
* To relocate a pool, declare it as extern in cc.h. Example for GCC:
* extern u8_t \_\_attribute\_\_((section(".onchip_mem"))) memp_memory_my_private_pool_base[];
*/