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sf: stmicro: dont send 4 bytes when reading status register

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I can't find anywhere in the datasheet that says the status register needs
3 dummy bytes sent to it before being able to read back the first real
result.  Tests on a Blackfin board show that after writing the opcode, the
status register starts coming back immediately.  So only write out the
read status register opcode before polling the result.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
CC: Jason McMullan <mcmullan@netapp.com>
CC: TsiChung Liew <Tsi-Chung.Liew@freescale.com>
This commit is contained in:
Mike Frysinger 2009-04-02 12:51:28 -04:00
parent 1abe365ffc
commit d9596ffbdc
1 changed files with 3 additions and 3 deletions
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6
drivers/mtd/spi/stmicro.c
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@ -133,12 +133,12 @@ static int stmicro_wait_ready(struct spi_flash *flash, unsigned long timeout)
struct spi_slave *spi = flash->spi;
unsigned long timebase;
int ret;
u8 cmd = CMD_M25PXX_RDSR;
u8 status;
u8 cmd[4] = { CMD_M25PXX_RDSR, 0xff, 0xff, 0xff };
ret = spi_xfer(spi, 32, &cmd[0], NULL, SPI_XFER_BEGIN);
ret = spi_xfer(spi, 8, &cmd, NULL, SPI_XFER_BEGIN);
if (ret) {
debug("SF: Failed to send command %02x: %d\n", cmd[0], ret);
debug("SF: Failed to send command %02x: %d\n", cmd, ret);
return ret;
}