FDS driver issue

[khodidas]

Hello,

Hope you guys are well !!!

We are using below SDK's for our range of product:

1. 11.0.0

2. 13.0.0

3. 13.1.0

4. 14.1.0

5. 15.2.0

6 15.3.0

As I come to know that you guys fixed issue of FDS in SDK16.0.0.

nRF5 SDK v16.0.0
------------------------
Release Date: October, 2019

*** Bug fixes
****************

** Drivers and libraries **

- FDS: fixed two bugs where a power loss at very specific times during garbage
collection could corrupt the file system, making FDS unable to initialize and return
FDS_ERR_NO_PAGES on initialization.
- FDS: fixed a bug that prevented using the last word of a flash page to save a record.

How can we fix this issue in above mention SDK we are using?

Do we have guide line to fix issue?

Thanks,

Nirav Patel

[Jørgen Holmefjord]

Hi,

It will be hard to explain the changes into the older SDKs, but I compared fds.c in SDK 15.3.0 and SDK 16.0.0, and the changes are the following:

The following function in SDK 15.3.0:

static bool page_is_erased(uint32_t const * const p_page_addr)
{
    for (uint32_t i = 0; i < FDS_PAGE_SIZE; i++)
    {
        if (*(p_page_addr + i) != FDS_ERASED_WORD)
        {
            return false;
        }
    }

    return true;
}

Has been replaced with the following function in SDK 16.0.0:

// A page can be tagged if it is entirely erased, or
// of the first word is fds magic word and the rest of it is erased.
static bool page_can_tag(uint32_t const * const p_page_addr)
{
    // This function should consider pages that have only the first half
    // of the fds page tag written as erased (taggable).
    // That is because the tag is two words long, and if the device
    // has rebooted after writing the first word, that would cause
    // the page to be unusable (since undefined and not fully erased).
    // By considering the first word as erased if it contains fds page tag,
    // the page can be re-tagged as necessary.

    if ((p_page_addr[FDS_PAGE_TAG_WORD_0] != FDS_ERASED_WORD) &&
        (p_page_addr[FDS_PAGE_TAG_WORD_0] != FDS_PAGE_TAG_MAGIC))
    {
        return false;
    }

    // Ignore the first word of the tag, we already checked that it is either erased or fds's.
    for (uint32_t i = FDS_PAGE_TAG_WORD_1; i < FDS_PAGE_SIZE; i++)
    {
        if (*(p_page_addr + i) != FDS_ERASED_WORD)
        {
            return false;
        }
    }

    return true;
}

And the function call is replaced inside pages_init().

There is also an addition further down in pages_init(), in the FDS_PAGE_SWAP case:

// This is a candidate for a potential new swap page, in case the
// current swap is going to be promoted to complete a GC instance.
m_gc.cur_page = page;

The header_check() function is also slightly modified, to check for erase word:

// It is important to also check for the record ID to be non-erased.
// It might happen that during GC, when records are copied in one operation,
// the device powers off after writing the first two words of the header.
// In that case the record would be considered valid, but its ID would
// corrupt the file system.
if (   (p_hdr->file_id    == FDS_FILE_ID_INVALID)
    || (p_hdr->record_key == FDS_RECORD_KEY_DIRTY)
    || (p_hdr->record_id  == FDS_ERASED_WORD))
{
    return FDS_HEADER_DIRTY;
}

Hope this helps.

Best regards,
Jørgen

[khodidas]

Hi Jorgen,

Thanks for the answer. 

I also need help for other SDK.

Let's wait for some Nordic guy response.