TDA2PXEVM: MTD(Memory Technology Device) Subsystem Write

Shantanu Joshi

Part Number: TDA2PXEVM

Hello All,

We are using MTD(Memory Technology Device) Subsystem provided abstraction layer from HLOS usecase to save some data in flash device and retrieve from the same.

We are using mtd4 which has 64k space to read and write.

Our data is around 800 bytes which we are saving on this sector. But in order to do so we need to write two times consecutively.

But we have checked for small bytes of data like 64 bytes in there we are able to read all the data correctly with single write only.

We are not getting exactly why we need to write two times for 800 bytes in order to read all the data correctly.

Inputs, Suggestions will be of great help.

Regards

Shantanu Joshi

over 5 years ago

0 Keerthy J over 5 years ago

TI__Guru**** 166310 points

Hi Shantanu,

Can you please share the exact commands that you are using in Linux to reproduce the issue
at our end.

Best Regards,
Keerthy

0 Shantanu Joshi over 5 years ago in reply to Keerthy J

Expert 1320 points

Hi Keerthy

Sharing you the small code for reading and writing small chunk of data with single write,

static int qspiInit = 1 ;
static unsigned char buf[64];
static int fd = 0;
mtd_info_t mtd_info;

fd = open("/dev/mtd4", O_RDWR);
ioctl(fd, MEMGETINFO, &mtd_info);

if(qspiInit)

{
        qspiInit = 0;
        erase_info_t ei;
        ei.length = mtd_info.erasesize;
        for(ei.start = 0; ei.start < mtd_info.size; ei.start += mtd_info.erasesize)
        {
            ioctl(fd, MEMUNLOCK, &ei);
            ioctl(fd, MEMERASE, &ei);
        }
        for(int i = 0; i< 64; i++)
        {
             buf[i] = 5;
        }
        lseek(fd, -mtd_info.erasesize, SEEK_END);
        write(fd, buf, sizeof(buf));

}

lseek(fd, -mtd_info.erasesize, SEEK_END);

read(fd, buf, sizeof(buf));

for(int j = 0; j< 64; j++)

{

Vps_printf("buf[%d]\n", j, buf[j]);

}

close(fd);

Regards

Shantanu

0 Keerthy J over 5 years ago in reply to Shantanu Joshi

TI__Guru**** 166310 points

Hi Shantanu,

If i understand the above is the working case. Can you share the non working test case with 800 Bytes written.

Also share the u-boot & kernel logs so we know the version.

Best Regards,
Keerthy

0 Keerthy J over 5 years ago in reply to Keerthy J

TI__Guru**** 166310 points

Hi Shantanu,

I do not have TDA2P at my end but i tried something very close to what you are trying on my am574x-idk which
is similar to TDA2P:

Step 1: Created a file of 800 bytes: dd if=/dev/urandom of=test bs=800 count=1

Step 2: ls -al test
-rw-r--r-- 1 root root 800 Sep 12 17:24 test

Ensured that test is created

Step 3: flash_erase /dev/mtd4 0 0

Step 4: mtd_debug write /dev/mtd4 0 800 test /* Write 800 bytes from test file to offset 0 of mtd4 flash */

Step 5: mtd_debug read /dev/mtd4 0 800 test1 /* Read 800 bytes from offset 0 of mtd4 flash to test1 file to */

Step 6: md5sum test
af13366b0cf79c93609607194f904ac2 test
root@am57xx-evm:~# md5sum test1
af13366b0cf79c93609607194f904ac2 test1

As you can see 800 bytes went through just fine.

Can you try the above?

Best Regards,
Keerthy

0 Shantanu Joshi over 5 years ago in reply to Keerthy J

Expert 1320 points

Hello Keerthy,

From above I can see if i am not wrong you have tested with linux commands. Can you try the same with a C function similar as me.

Please do note that in 800 bytes I am writing consists of a structure which has different structure elements as well as elements of different data types such as char,short,float,int.

one of the structure element has size of 544 bytes out of 800 bytes I am writing.

Regards

Shantanu

0 Keerthy J over 5 years ago in reply to Shantanu Joshi

TI__Guru**** 166310 points

Shantanu,

Can you try writing your contents to a file once you boot to prompt & try the commands i have shown
to be sure that linux mtd commands are working fine before we get to you code?

Best Regards,
Keerthy

0 Shantanu Joshi over 5 years ago in reply to Keerthy J

Expert 1320 points

Keerthy,

Ok I will do that.

Regards

Shantanu

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TDA2PXEVM: MTD(Memory Technology Device) Subsystem Write