Re: flashcp

[Tobias Simon <tobias.simon@sp-ss.de>]

Hello Jörn,

> 1. You're off-by-one when (filestat.st_size % mtd.erasesize) yields
> zero.
Oops, you're right!

> 2. In principle the "patch" looks fine.  Except that it should be a
> patch and probably follow kernel coding style or something similar.

--- mtd-utils-1.0.0/flashcp.c   2006-04-30 22:59:15.000000000 +0200
+++ mtd-utils-1.0.0_new/flashcp.c       2007-07-19 22:57:25.000000000 +0200
@@ -258,7 +258,14 @@
 #warning "Check for smaller erase regions"

    erase.start = 0;
-   erase.length = filestat.st_size & ~(mtd.erasesize - 1);
+
+   if (filestat.st_size % mtd.erasesize) {
+      erase.length = filestat.st_size + mtd.erasesize - (filestat.st_size % 
mtd.erasesize);
+   }
+   else {
+      erase.length = filestat.st_size;
+   }
+
    if (filestat.st_size % mtd.erasesize) erase.length += mtd.erasesize;
    if (flags & FLAG_VERBOSE)
         {

> 3. I keep wondering whether the oddball erasesize of dataflash makes
> sense.  Why did they pick 1056, the exact size of two 512 Byte nand
> pages with the standard 16 Bytes of OOB each?  Could they need ECC as
> well and should the "spare" 32 bytes be used for that instead?
The standard page/erase-size of the AT45DB642x Dataflash we use 
(http://www.atmel.com/dyn/resources/prod_documents/doc3542.pdf) is 1056.
Although it is configurable to 1024 by software, the atmel_mtd.c driver 
(linux-2.6.21) uses 1056 as the erase size. The driver itself is full of odd 
erase-sizes: 
/*
 * Detect and initialize DataFlash device:
 *
 *   Device      Density         ID code          #Pages PageSize  Offset
 *   AT45DB011B  1Mbit   (128K)  xx0011xx (0x0c)    512    264      9
 *   AT45DB021B  2Mbit   (256K)  xx0101xx (0x14)   1025    264      9
 *   AT45DB041B  4Mbit   (512K)  xx0111xx (0x1c)   2048    264      9
 *   AT45DB081B  8Mbit   (1M)    xx1001xx (0x24)   4096    264      9
 *   AT45DB0161B 16Mbit  (2M)    xx1011xx (0x2c)   4096    528     10
 *   AT45DB0321B 32Mbit  (4M)    xx1101xx (0x34)   8192    528     10
 *   AT45DB0642  64Mbit  (8M)    xx111xxx (0x3c)   8192   1056     11
 *   AT45DB1282  128Mbit (16M)   xx0100xx (0x10)  16384   1056     11
 */


-- 
Mit freundlichem Gruß / Kind regards

Tobias Simon
- Entwickler -

Simon + Puschmann Software-Systeme GbR
Tobias Simon, Andre Puschmann

Bergrat-Voigt-Straße 13
98693 Ilmenau
Tel.: 0173/2752144
E-Mail: tobias.simon@sp-ss.de
Internet: http://www.sp-ss.de

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