| Message ID | 1386278524-25669-1-git-send-email-u.kleine-koenig@pengutronix.de |
|---|---|
| State | Accepted, archived |
| Headers | show |
(Huang: a few comments are directed at you below) Hi Uwe, On Thu, Dec 05, 2013 at 10:22:04PM +0100, Uwe Kleine-König wrote: > According to the Open NAND Flash Interface Specification (ONFI) Revision > 3.1 "Parameters are always transferred on the lower 8-bits of the data > bus." for the Get Features and Set Features commands. > > So using read_buf and write_buf is wrong for 16-bit wide nand chips as > they use I/O[15:0]. The Get Features command is easily fixed using 4 > times the read_byte callback. For Set Features implement a new > overwritable callback "write_byte". Still I expect the default to work > just fine for all controllers and making it overwriteable was just done > for symmetry. > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > --- > Changes since v2, sent with > Message-Id: 1362415655-13073-1-git-send-email-u.kleine-koenig@pengutronix.de: > > - use a proper uint16_t instead of a 2 byte array to pass to chip->write_buf > to fix endianess issue. Noticed by David Woodhouse. (This also gets rid of > the Compound Literal that catched David's eye.) > > Changes since v3, sent with > Message-id:1385500515-5376-1-git-send-email-u.kleine-koenig@pengutronix.de (v3) > > - drop whitespace cleanup > - support resetting to 16 bit width function on 2nd call of nand_set_defaults Thanks for the changes. This patch looks good to me, and I think it can go in regardless of our other x8/x16 buswidth solutions. I don't have a good x16 setup yet, but I believe Ezequiel did some testing on v3 (is this a "Tested-by"?). I'll probably try this out on my x8 setups when I get a chance sometime this week. > drivers/mtd/nand/nand_base.c | 57 ++++++++++++++++++++++++++++++++++++++++++-- > include/linux/mtd/nand.h | 3 +++ > 2 files changed, 58 insertions(+), 2 deletions(-) > > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c > index bd39f7b..3a6e95f 100644 > --- a/drivers/mtd/nand/nand_base.c > +++ b/drivers/mtd/nand/nand_base.c > @@ -202,6 +202,51 @@ static void nand_select_chip(struct mtd_info *mtd, int chipnr) > } > > /** > + * nand_write_byte - [DEFAULT] write single byte to chip > + * @mtd: MTD device structure > + * @byte: value to write > + * > + * Default function to write a byte to I/O[7:0] > + */ > +static void nand_write_byte(struct mtd_info *mtd, uint8_t byte) > +{ > + struct nand_chip *chip = mtd->priv; > + > + chip->write_buf(mtd, &byte, 1); Side issue: Huang, this is another potential pitfall for GPMI, as you will again be performing DMA on the stack. > +} > + > +/** > + * nand_write_byte16 - [DEFAULT] write single byte to a chip with width 16 > + * @mtd: MTD device structure > + * @byte: value to write > + * > + * Default function to write a byte to I/O[7:0] on a 16-bit wide chip. > + */ > +static void nand_write_byte16(struct mtd_info *mtd, uint8_t byte) > +{ > + struct nand_chip *chip = mtd->priv; > + uint16_t word = byte; > + > + /* > + * It's not entirely clear what should happen to I/O[15:8] when writing > + * a byte. The ONFi spec (Revision 3.1; 2012-09-19, Section 2.16) reads: > + * > + * When the host supports a 16-bit bus width, only data is > + * transferred at the 16-bit width. All address and command line > + * transfers shall use only the lower 8-bits of the data bus. During > + * command transfers, the host may place any value on the upper > + * 8-bits of the data bus. During address transfers, the host shall > + * set the upper 8-bits of the data bus to 00h. > + * > + * One user of the write_byte callback is nand_onfi_set_features. The > + * four parameters are specified to be written to I/O[7:0], but this is > + * neither an address nor a command transfer. Let's assume a 0 on the > + * upper I/O lines is OK. > + */ > + chip->write_buf(mtd, &word, 2); Huang: same here. So you see how this type of patch can easily trigger the maintainability problems that are inherent when gpmi-nand does things differently than other drivers? > +} > + > +/** > * nand_write_buf - [DEFAULT] write buffer to chip > * @mtd: MTD device structure > * @buf: data buffer Brian
On Mon, Dec 16, 2013 at 09:48:25PM -0800, Brian Norris wrote: [..] > > I don't have a good x16 setup yet, but I believe Ezequiel did some > testing on v3 (is this a "Tested-by"?). I'll probably try this out on my > x8 setups when I get a chance sometime this week. > No, I couldn't do a proper test of this one, although I remembered a tested a branch based on this patch. The problem was I couldn't find time to figure out how to test the GetFeatures and SetFeatures command. Hints? I can try to give it a test this weekend.
On Tue, Dec 17, 2013 at 06:46:49PM -0300, Ezequiel Garcia wrote: > The problem was I couldn't find time to figure out how to test the GetFeatures > and SetFeatures command. Hints? Browse the ONFI spec for something you should expect to be able to read (for GET_FEATURES). Incidentally, I've been testing {GET,SET}_FEATURES with my Micron MLC that need read-retry, but you might not have any flash that support that. Brian
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index bd39f7b..3a6e95f 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -202,6 +202,51 @@ static void nand_select_chip(struct mtd_info *mtd, int chipnr) } /** + * nand_write_byte - [DEFAULT] write single byte to chip + * @mtd: MTD device structure + * @byte: value to write + * + * Default function to write a byte to I/O[7:0] + */ +static void nand_write_byte(struct mtd_info *mtd, uint8_t byte) +{ + struct nand_chip *chip = mtd->priv; + + chip->write_buf(mtd, &byte, 1); +} + +/** + * nand_write_byte16 - [DEFAULT] write single byte to a chip with width 16 + * @mtd: MTD device structure + * @byte: value to write + * + * Default function to write a byte to I/O[7:0] on a 16-bit wide chip. + */ +static void nand_write_byte16(struct mtd_info *mtd, uint8_t byte) +{ + struct nand_chip *chip = mtd->priv; + uint16_t word = byte; + + /* + * It's not entirely clear what should happen to I/O[15:8] when writing + * a byte. The ONFi spec (Revision 3.1; 2012-09-19, Section 2.16) reads: + * + * When the host supports a 16-bit bus width, only data is + * transferred at the 16-bit width. All address and command line + * transfers shall use only the lower 8-bits of the data bus. During + * command transfers, the host may place any value on the upper + * 8-bits of the data bus. During address transfers, the host shall + * set the upper 8-bits of the data bus to 00h. + * + * One user of the write_byte callback is nand_onfi_set_features. The + * four parameters are specified to be written to I/O[7:0], but this is + * neither an address nor a command transfer. Let's assume a 0 on the + * upper I/O lines is OK. + */ + chip->write_buf(mtd, &word, 2); +} + +/** * nand_write_buf - [DEFAULT] write buffer to chip * @mtd: MTD device structure * @buf: data buffer @@ -2716,6 +2761,7 @@ static int nand_onfi_set_features(struct mtd_info *mtd, struct nand_chip *chip, int addr, uint8_t *subfeature_param) { int status; + int i; if (!chip->onfi_version || !(le16_to_cpu(chip->onfi_params.opt_cmd) @@ -2723,7 +2769,9 @@ static int nand_onfi_set_features(struct mtd_info *mtd, struct nand_chip *chip, return -EINVAL; chip->cmdfunc(mtd, NAND_CMD_SET_FEATURES, addr, -1); - chip->write_buf(mtd, subfeature_param, ONFI_SUBFEATURE_PARAM_LEN); + for (i = 0; i < ONFI_SUBFEATURE_PARAM_LEN; ++i) + chip->write_byte(mtd, subfeature_param[i]); + status = chip->waitfunc(mtd, chip); if (status & NAND_STATUS_FAIL) return -EIO; @@ -2740,6 +2788,8 @@ static int nand_onfi_set_features(struct mtd_info *mtd, struct nand_chip *chip, static int nand_onfi_get_features(struct mtd_info *mtd, struct nand_chip *chip, int addr, uint8_t *subfeature_param) { + int i; + if (!chip->onfi_version || !(le16_to_cpu(chip->onfi_params.opt_cmd) & ONFI_OPT_CMD_SET_GET_FEATURES)) @@ -2749,7 +2799,8 @@ static int nand_onfi_get_features(struct mtd_info *mtd, struct nand_chip *chip, memset(subfeature_param, 0, ONFI_SUBFEATURE_PARAM_LEN); chip->cmdfunc(mtd, NAND_CMD_GET_FEATURES, addr, -1); - chip->read_buf(mtd, subfeature_param, ONFI_SUBFEATURE_PARAM_LEN); + for (i = 0; i < ONFI_SUBFEATURE_PARAM_LEN; ++i) + *subfeature_param++ = chip->read_byte(mtd); return 0; } @@ -2812,6 +2863,8 @@ static void nand_set_defaults(struct nand_chip *chip, int busw) chip->block_markbad = nand_default_block_markbad; if (!chip->write_buf || chip->write_buf == nand_write_buf) chip->write_buf = busw ? nand_write_buf16 : nand_write_buf; + if (!chip->write_byte || chip->write_byte == nand_write_byte) + chip->write_byte = busw ? nand_write_byte16 : nand_write_byte; if (!chip->read_buf || chip->read_buf == nand_read_buf) chip->read_buf = busw ? nand_read_buf16 : nand_read_buf; if (!chip->scan_bbt) diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h index 9e6c8f9..e843942 100644 --- a/include/linux/mtd/nand.h +++ b/include/linux/mtd/nand.h @@ -432,6 +432,8 @@ struct nand_buffers { * flash device. * @read_byte: [REPLACEABLE] read one byte from the chip * @read_word: [REPLACEABLE] read one word from the chip + * @write_byte [REPLACEABLE] write a single byte to the chip on the + * low 8 I/O lines * @write_buf: [REPLACEABLE] write data from the buffer to the chip * @read_buf: [REPLACEABLE] read data from the chip into the buffer * @select_chip: [REPLACEABLE] select chip nr @@ -521,6 +523,7 @@ struct nand_chip { uint8_t (*read_byte)(struct mtd_info *mtd); u16 (*read_word)(struct mtd_info *mtd); + void (*write_byte)(struct mtd_info *mtd, uint8_t byte); void (*write_buf)(struct mtd_info *mtd, const uint8_t *buf, int len); void (*read_buf)(struct mtd_info *mtd, uint8_t *buf, int len); void (*select_chip)(struct mtd_info *mtd, int chip);
According to the Open NAND Flash Interface Specification (ONFI) Revision 3.1 "Parameters are always transferred on the lower 8-bits of the data bus." for the Get Features and Set Features commands. So using read_buf and write_buf is wrong for 16-bit wide nand chips as they use I/O[15:0]. The Get Features command is easily fixed using 4 times the read_byte callback. For Set Features implement a new overwritable callback "write_byte". Still I expect the default to work just fine for all controllers and making it overwriteable was just done for symmetry. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- Changes since v2, sent with Message-Id: 1362415655-13073-1-git-send-email-u.kleine-koenig@pengutronix.de: - use a proper uint16_t instead of a 2 byte array to pass to chip->write_buf to fix endianess issue. Noticed by David Woodhouse. (This also gets rid of the Compound Literal that catched David's eye.) Changes since v3, sent with Message-id:1385500515-5376-1-git-send-email-u.kleine-koenig@pengutronix.de (v3) - drop whitespace cleanup - support resetting to 16 bit width function on 2nd call of nand_set_defaults drivers/mtd/nand/nand_base.c | 57 ++++++++++++++++++++++++++++++++++++++++++-- include/linux/mtd/nand.h | 3 +++ 2 files changed, 58 insertions(+), 2 deletions(-)