DMA to eMMC can only talk to SYSRAM but not RAM (SRAM1, SRAM2, SRAM3)

[cbcooper]

I've got a custom board with an STM32MP135AAE3 talking to an eMMC (THGBMTG5D1LBAIL if it makes a difference). I've discovered that if I write from SYSTEM to the eMMC using DMA (HAL_MMC_WriteBlocks_DMA) it works fine, but if I use anything in RAM (SRAM1, SRAM2, or SRAM3) as the source, the DMA fails immediately.

If it helps, the SDMMC2 registers inside SDMMC2_IRQHandler() are: STA=0x8001010; DCOUNT=0x200; DCTRL=0x90; IDMACTRL=0x1; MASK=0x11A

Is this a known limitation of the IDMA? If not, is it something I'm somehow initializing incorrectly?

[PatrickF]

Hi @cbcooper 

Maybe check that ETZPC configuration for SDMMC2, SYSRAM and SRAMx are consistent.

Check that the right SRAMs addresses are used for SDMMC DMA.

Regards.

[cbcooper]

I think you're right about the ETZPC configuration (this is the first time I've programmed an STM32 chip where I had to think about secure vs. non-secure memory).  All I had was this line:

LL_ETZPC_SetSecureSysRamSize(ETZPC, 0);

but if I add these 3 lines;

  HAL_ETZPC_Set_SRAM1_PeriphProtection(ETZPC, LL_ETZPC_PERIPH_PROTECTION_READ_WRITE_NONSECURE);
  HAL_ETZPC_Set_SRAM2_PeriphProtection(ETZPC, LL_ETZPC_PERIPH_PROTECTION_READ_WRITE_NONSECURE);
  HAL_ETZPC_Set_SRAM3_PeriphProtection(ETZPC, LL_ETZPC_PERIPH_PROTECTION_READ_WRITE_NONSECURE);

then STM32_Programmer_CLI.exe hangs when trying to download the application. 

Why would the download hang?  I assumed STM32_Programmer_CLI. would download the application first and succeed at that, and then run the program (which could fail/crash/hang if those lines are wrong) but how can adding those lines affect the download?

[cbcooper]

Is the BootROM only able to upload into SYSRAM (and not SRAM1/SRAM2/SRAM3)?  Adding those 3 lines increased the payload size from 0x1F57C = 128,380 bytes to 0x20588 = 132,488 bytes.  I have a check in my LD file:

ASSERT(. <= ORIGIN(RAM) + LENGTH(RAM), "RAM overflow: sections exceed available RAM")

where

MEMORY {
    SYSRAM_BASE (rwx)   : ORIGIN = 0x2FFE0000, LENGTH = 128K
    SRAM1_BASE (rwx)    : ORIGIN = 0x30000000, LENGTH = 16K
    SRAM2_BASE (rwx)    : ORIGIN = 0x30004000, LENGTH = 8K
    SRAM3_BASE (rwx)    : ORIGIN = 0x30006000, LENGTH = 8K
    /* InternalMEM = SYSRAM + SRAM1 + SRAM2 + SRAM3 */
    InternalMEM (rwx)   : ORIGIN = 0x2FFE0000, LENGTH = 160K
    DDR_BASE (rwx)      : ORIGIN = 0xC0000000, LENGTH = 128M
}

/* Select Memory in which code has to be placed and offset of code from start of this memory */ 
REGION_ALIAS("RAM", InternalMEM);

but do I instead need to check

ASSERT(. <= ORIGIN(SYSRAM_BASE) + LENGTH(SYSRAM_BASE), "RAM overflow: sections exceed available RAM")

[PatrickF · Accepted solution]

Hi,

I think this the root cause as FSBL loaded by BootROM is limited to 128KB on STM32MP13
https://wiki.st.com/stm32mpu/wiki/STM32_MPU_ROM_code_overview#On_STM32MP1-lines_4

Regards.