When writing buffers that are not 32 bit aligned data loss occurs.
This can also occur when the total transfer size is not a multiple of 4 bytes since the extra bytes are written first causing the rest to be unaligned.
This can be seen by writing to SPI flash a 57 byte file containing 00 01 .. 38:
U-Boot > dhcp data.bin ... Bytes transferred = 57 (39 hex) U-Boot > md.b $loadaddr 72000000: 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f ................ 72000010: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f ................ 72000020: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f !"#$%&'()*+,-./ 72000030: 30 31 32 33 34 35 36 37 38 ff ff ff ff ff ff ff 012345678....... U-Boot > sf write $loadaddr 0 $filesize
U-Boot > mw.b $loadaddr ff 100 U-Boot > sf read $loadaddr 0 100 U-Boot > md.b $loadaddr 72000000: 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f ................ 72000010: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f ................ 72000020: 20 21 22 23 24 29 2a 2b 2c 31 32 33 34 ff ff ff !"#$)*+,1234... 72000030: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
[bytes 25-28, 2d-30, 35-38 are missing]
Activating debug in the write command gave: spi_xchg_single: bitlen 256 dout 0x72000000 din 0x0 Sending SPI 0x10203 Sending SPI 0x4050607 Sending SPI 0x8090a0b Sending SPI 0xc0d0e0f Sending SPI 0x10111213 Sending SPI 0x14151617 Sending SPI 0x18191a1b Sending SPI 0x1c1d1e1f SPI Rx: 0xffffffff 0xffffffff ... SPI Rx: 0xffffffff 0xffffffff spi_xchg_single: bitlen 200 dout 0x72000020 din 0x0 Sending SPI 0x20 Sending SPI 0x21222324 Sending SPI 0x292a2b2c <=== What happened to 25262728? Sending SPI 0x31323334 Sending SPI 0xffffffff ... SF: program success 57 bytes @ 0x0
The problem was that the pointer was being incremented twice for the non aligned case.
Signed-off-by: Martin Fuzzey mfuzzey@parkeon.com --- drivers/spi/mxc_spi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/spi/mxc_spi.c b/drivers/spi/mxc_spi.c index 859c43f..964a2b7 100644 --- a/drivers/spi/mxc_spi.c +++ b/drivers/spi/mxc_spi.c @@ -274,8 +274,8 @@ int spi_xchg_single(struct spi_slave *slave, unsigned int bitlen, } else { data = *(u32 *)dout; data = cpu_to_be32(data); + dout += 4; } - dout += 4; } debug("Sending SPI 0x%x\n", data); reg_write(®s->txdata, data);