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author | Len Brown <len.brown@intel.com> | 2010-08-15 01:06:31 -0400 |
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committer | Len Brown <len.brown@intel.com> | 2010-08-15 01:06:31 -0400 |
commit | 95ee46aa8698f2000647dfb362400fadbb5807cf (patch) | |
tree | e5a05c7297f997e191c73091934e42e3195c0e40 /Documentation/blackfin/bfin-spi-notes.txt | |
parent | cfa806f059801dbe7e435745eb2e187c8bfe1e7f (diff) | |
parent | 92fa5bd9a946b6e7aab6764e7312e4e3d9bed295 (diff) | |
download | linux-95ee46aa8698f2000647dfb362400fadbb5807cf.tar.bz2 |
Merge branch 'linus' into release
Conflicts:
drivers/acpi/debug.c
Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'Documentation/blackfin/bfin-spi-notes.txt')
-rw-r--r-- | Documentation/blackfin/bfin-spi-notes.txt | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/Documentation/blackfin/bfin-spi-notes.txt b/Documentation/blackfin/bfin-spi-notes.txt new file mode 100644 index 000000000000..556fa877f2e8 --- /dev/null +++ b/Documentation/blackfin/bfin-spi-notes.txt @@ -0,0 +1,14 @@ +SPI Chip Select behavior: + +With the Blackfin on-chip SPI peripheral, there is some logic tied to the CPHA +bit whether the Slave Select Line is controlled by hardware (CPHA=0) or +controlled by software (CPHA=1). However, the Linux SPI bus driver assumes that +the Slave Select is always under software control and being asserted during +the entire SPI transfer. - And not just bits_per_word duration. + +In most cases you can utilize SPI MODE_3 instead of MODE_0 to work-around this +behavior. If your SPI slave device in question requires SPI MODE_0 or MODE_2 +timing, you can utilize the GPIO controlled SPI Slave Select option instead. + +You can even use the same pin whose peripheral role is a SSEL, +but use it as a GPIO instead. |