Corrupt my NAND flash device

[Eugeny Mints]

Hi all,

> -----Original Message-----
> From: Eugeny Mints
> Sent: Monday, August 18, 2003 3:37 PM
> To: samoutin at hotbox.ru
> Cc: David Woodhouse; linux-mtd at lists.infradead.org
> Subject: Fw: corrupt my NAND flash device
> 
> Alex, all,
> 
> >Alex Samoutin samoutin at hotbox.ru
> >Wed Jul 2 11:43:11 BST 2003
> 
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> 
> >Hi Thomas,
> >Sorry for big delay with answer - I had no hardware to test. Now I 
> >got
> my
> >CerfCube 405ep back and can play with it.
> >So I had two problems
> 
> >  1.. Write verify sometimes fail
> >  2.. Write operation during erase sometimes cause data corruption
> 
> Could you please describe you test which detects the first problem? I 
> have the same, but it arises very seldom and unstable. I'd like to be 
> able to reproduce the bug predictably.
> 
> >Hardware details :
> >- NAND chip Toshiba TC58256AFT
> >- ALE/CLE and CE connected to GPIO
> >- R/B pin connected to GPIO and I use ready function which reads it
> pin.
> >- I played with different timings - even slowest setting gets  me the
> same
> >result
> 
> >1-st problem was solved by applying new MTD snapshot  (Jun 26). It's
> look
> >like nand_deselect(); nand_select() fixes the problem.
> 
> It is interesting - this fix doesn't help me:( (I have MIPS Au1100 and

> Toshiba TC58256AFTI ) More over, I discovered that fix proposed by 
> David in the latests
> (august) snapshots (reset before write command) hangs my system during

> eraseall:(

Ok, eventually I discovered the core of the problems. In fact, there are
several problems. 

Problem 1.

In all snapshots, in which there is no auxiliary routine
nand_write_bufer there is the bug in nand_command (in RESET command
implementation):

----code---
...
case NAND_CMD_STATUS:
                return;

        case NAND_CMD_RESET:
                if (this->dev_ready)
                        break;
                this->hwcontrol(mtd, NAND_CTL_SETCLE);
                writeb (NAND_CMD_STATUS, NAND_IO_ADDR);
                this->hwcontrol(mtd, NAND_CTL_CLRCLE);
                while ( !(this->read_byte(mtd) & 0x40));
                return;

        /* This applies to read commands */
        default:
...
---end code---

should be:

---code----

...
case NAND_CMD_STATUS:
                return;

        case NAND_CMD_RESET:
                if (this->dev_ready)
                        break;
                this->hwcontrol(mtd, NAND_CTL_SETCLE);
+               NAND_IO_ADDR = this->IO_ADDR_W;
                writeb (NAND_CMD_STATUS, NAND_IO_ADDR);
                this->hwcontrol(mtd, NAND_CTL_CLRCLE);
                while ( !(this->read_byte(mtd) & 0x40));
                return;

        /* This applies to read commands */
        default:
...
---end code---

Problem 2.

My board falls in the infinite loop at (!(this->read_byte(mtd) & 0x40));
even with the latest snapshot 18.08.2003 on RESET command. Interesting,
that it happens not from the very begging but just when write_oob has
executed (during eraseall) for about a half of the flash. 

I found that insertion of udelay() before issuing STATUS command helps.
Any suggestions?

> 
> 
> >However  after applying new MTD release the 2-nd problem still
> remained.
> >Then I comment out erase abort in nand_get_chip (as you suggested) 
> >and
> it
> >fixes my second problem!
> >Could you remove this erase abort from MTD source? I think it will 
> >not affect much on efficiency.

Possibly second Alex's problem may be solved by udelay() also? And there
is no need to comment out erase abort? 

> 
> My second problem is that system hangs if the device is filled once 
> and an attempt to re-use previously used sectors is made. Comment out 
> erase abort in nand_get_chip fixes my second problem too.
> 

Regards,
 		Eugeny