| Message ID | ea2442770809150537p538f5298s9b5b003a1825b09f@mail.gmail.com |
|---|---|
| State | Accepted |
| Headers | show |
On Mon, Sep 15, 2008 at 02:37:29PM +0200, Karl Beldan wrote: > Some chips require a RESET after power-up (e.g. Micron MT29FxGxxxxx). > The first command sent is NAND_CMD_READID. > Issue a NAND_CMD_RESET in nand_scan_ident before reading the device id. > Tested with an MT29F4G08AAC. This seems sensible to me, we don't really know what state the NAND chip is in. Does there need to be a delay after sending the reset command before attempting to read the chip's identity? > Signed-off-by: Karl Beldan <karl.beldan@gmail.com> > --- > Prior to resetting, the chip gives a correct first ID byte though. > > > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c > index d1129ba..2cfac9b 100644 > --- a/drivers/mtd/nand/nand_base.c > +++ b/drivers/mtd/nand/nand_base.c > @@ -2318,6 +2318,12 @@ static struct nand_flash_dev > *nand_get_flash_type(struct mtd_info *mtd, > /* Select the device */ > chip->select_chip(mtd, 0); > > + /* > + * Reset the chip, required by some chips (e.g. Micron MT29FxGxxxxx) > + * after power-up > + */ > + chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1); > + > /* Send the command for reading device ID */ > chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1); > > @@ -2488,6 +2494,8 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips) > /* Check for a chip array */ > for (i = 1; i < maxchips; i++) { > chip->select_chip(mtd, i); > + /* See comment in nand_get_flash_type for reset */ > + chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1); > /* Send the command for reading device ID */ > chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1); > /* Read manufacturer and device IDs */ > > ______________________________________________________ > Linux MTD discussion mailing list > http://lists.infradead.org/mailman/listinfo/linux-mtd/
Ben Dooks wrote: > On Mon, Sep 15, 2008 at 02:37:29PM +0200, Karl Beldan wrote: >> Some chips require a RESET after power-up (e.g. Micron MT29FxGxxxxx). >> The first command sent is NAND_CMD_READID. >> Issue a NAND_CMD_RESET in nand_scan_ident before reading the device id. >> Tested with an MT29F4G08AAC. > > This seems sensible to me, we don't really know what state the NAND > chip is in. > > Does there need to be a delay after sending the reset command before > attempting to read the chip's identity? > There's the tWB + tRST delay which is handled by the CMD_RESET case in nand_command if that's what you were thinking of. Tested both R/B and STATUS_READY code paths. >> Signed-off-by: Karl Beldan <karl.beldan@gmail.com> >> --- >> Prior to resetting, the chip gives a correct first ID byte though. >> >> >> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c >> index d1129ba..2cfac9b 100644 >> --- a/drivers/mtd/nand/nand_base.c >> +++ b/drivers/mtd/nand/nand_base.c >> @@ -2318,6 +2318,12 @@ static struct nand_flash_dev >> *nand_get_flash_type(struct mtd_info *mtd, >> /* Select the device */ >> chip->select_chip(mtd, 0); >> >> + /* >> + * Reset the chip, required by some chips (e.g. Micron MT29FxGxxxxx) >> + * after power-up >> + */ >> + chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1); >> + >> /* Send the command for reading device ID */ >> chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1); >> >> @@ -2488,6 +2494,8 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips) >> /* Check for a chip array */ >> for (i = 1; i < maxchips; i++) { >> chip->select_chip(mtd, i); >> + /* See comment in nand_get_flash_type for reset */ >> + chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1); >> /* Send the command for reading device ID */ >> chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1); >> /* Read manufacturer and device IDs */ >> >> ______________________________________________________ >> Linux MTD discussion mailing list >> http://lists.infradead.org/mailman/listinfo/linux-mtd/ >
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index d1129ba..2cfac9b 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -2318,6 +2318,12 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd, /* Select the device */ chip->select_chip(mtd, 0); + /* + * Reset the chip, required by some chips (e.g. Micron MT29FxGxxxxx) + * after power-up + */ + chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1); + /* Send the command for reading device ID */ chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
Some chips require a RESET after power-up (e.g. Micron MT29FxGxxxxx). The first command sent is NAND_CMD_READID. Issue a NAND_CMD_RESET in nand_scan_ident before reading the device id. Tested with an MT29F4G08AAC. Signed-off-by: Karl Beldan <karl.beldan@gmail.com>