[HELP] Is the stm32_dmapreflight check necessary (stm32h7)

[snikeguo]

Description

Is the stm32_dmapreflight check necessary? I can still successfully mount the filesystem and read/write when CONFIG_ARCH_HAVE_SDIO_PREFLIGHT is set to 'n'. However, setting it to 'y' results in a "dcache unaligned" error.

#if defined(CONFIG_ARMV7M_DCACHE) && !defined(CONFIG_ARMV7M_DCACHE_WRITETHROUGH)
  /* buffer alignment is required for DMA transfers with dcache in buffered
   * mode (not write-through) because a) arch_invalidate_dcache could lose
   * buffered writes and b) arch_flush_dcache could corrupt adjacent memory
   * if the maddr and the mend+1, the next next address are not on
   * ARMV7M_DCACHE_LINESIZE boundaries.
   */

  if (buffer != priv->rxfifo &&
      (((uintptr_t)buffer & (ARMV7M_DCACHE_LINESIZE - 1)) != 0 ||
      ((uintptr_t)(buffer + buflen) & (ARMV7M_DCACHE_LINESIZE - 1)) != 0))
    {
      mcerr("dcache unaligned "
            "buffer:%p end:%p\n",
            buffer, buffer + buflen - 1);
      return -EFAULT;
    }
#endif

  return 0;

Verification

• I have verified before submitting the report.

[acassis]

@snikeguo the preflight normally is used to double check that the buffer is correctly aligned, that the memory source is DMA capable, etc. It also could be used to enable some MCU specific feature required before executing the DMA transfer.

I think when capabilities were included into NuttX the right comments missed:

# MMC/SD-related platform capabilities

config ARCH_HAVE_SDIO
        bool
        default n

config ARCH_HAVE_SDIOWAIT_WRCOMPLETE
        bool
        default n

config ARCH_HAVE_SDIO_PREFLIGHT
        bool
        default n