* nand_command
@ 2004-09-22 11:13 Artem B. Bityuckiy
2004-09-23 6:25 ` nand_command Thomas Gleixner
0 siblings, 1 reply; 2+ messages in thread
From: Artem B. Bityuckiy @ 2004-09-22 11:13 UTC (permalink / raw)
To: tglx; +Cc: linux-mtd
Hello.
Thomas, as you sad, "only the ones with 512byte pagesize" NAND chips
support operations like this:
1. NAND_CND_READ0, NAND_CMD_SEQIN, <addr>, <data>, NAND_CMD_PAGEPRG
2. NAND_CND_READ1, NAND_CMD_SEQIN, <addr>, <data>, NAND_CMD_PAGEPRG
3. NAND_CND_READOOB, NAND_CMD_SEQIN, <addr>, <data>, NAND_CMD_PAGEPRG
The first chain - programm page starting from the beginning
The second chain - programm page starting from the second half
The third chain - programm starting from OOB area.
Chips with 256-byte page support only one programm operation like this:
NAND_CMD_SEQIN, <addr>, <data>, NAND_CMD_PAGEPRG
Correct? (I can't find any 256-byte page Flash manual to check)
If I'm correct, I propose to change a little the default command
function for "small page" devices (nand_base.c, nand_command). The code
is like this:
static void nand_command (struct mtd_info *mtd, unsigned command, int
column, int page_addr)
{
register struct nand_chip *this = mtd->priv;
/* Begin command latch cycle */
this->hwcontrol(mtd, NAND_CTL_SETCLE);
/*
* Write out the command to the device.
*/
if (command == NAND_CMD_SEQIN) {
int readcmd;
if (column >= mtd->oobblock) {
/* OOB area */
column -= mtd->oobblock;
readcmd = NAND_CMD_READOOB;
} else if (column < 256) {
/* First 256 bytes --> READ0 */
readcmd = NAND_CMD_READ0;
} else {
column -= 256;
readcmd = NAND_CMD_READ1;
}
this->write_byte(mtd, readcmd);
}
this->write_byte(mtd, command);
.............
It can be seen that for "small page" devices the NAND_CMD_READ0 command
is also input before NAND_CMD_SEQIN. This is not big error, but if to be
pedantic, this isn't needed.
I propose to change this code the following way:
static void nand_command (struct mtd_info *mtd, unsigned command, int
column, int page_addr)
{
register struct nand_chip *this = mtd->priv;
/* Begin command latch cycle */
this->hwcontrol(mtd, NAND_CTL_SETCLE);
/*
* Write out the command to the device.
*/
if (mtd->oobblock > 256 && command == NAND_CMD_SEQIN) { /*
<----- here */
int readcmd;
if (column >= mtd->oobblock) {
/* OOB area */
column -= mtd->oobblock;
readcmd = NAND_CMD_READOOB;
} else if (column < 256) {
/* First 256 bytes --> READ0 */
readcmd = NAND_CMD_READ0;
} else {
column -= 256;
readcmd = NAND_CMD_READ1;
}
this->write_byte(mtd, readcmd);
}
this->write_byte(mtd, command);
.............
Comments?
--
Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: nand_command
2004-09-22 11:13 nand_command Artem B. Bityuckiy
@ 2004-09-23 6:25 ` Thomas Gleixner
0 siblings, 0 replies; 2+ messages in thread
From: Thomas Gleixner @ 2004-09-23 6:25 UTC (permalink / raw)
To: Artem B. Bityuckiy; +Cc: linux-mtd
Hello Artem,
On Wed, 2004-09-22 at 13:13, Artem B. Bityuckiy wrote:
> Chips with 256-byte page support only one programm operation like this:
> NAND_CMD_SEQIN, <addr>, <data>, NAND_CMD_PAGEPRG
> Correct? (I can't find any 256-byte page Flash manual to check)
Yes, those chips are out of production.
> If I'm correct, I propose to change a little the default command
> function for "small page" devices (nand_base.c, nand_command). The code
> is like this:
As this is legacy only and it does not influence the functionality, why
bother to have an additional check for something which isnt available
anyway.
tglx
^ permalink raw reply [flat|nested] 2+ messages in thread
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