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author | Michal Marek <mmarek@suse.cz> | 2010-10-12 15:09:06 +0200 |
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committer | Michal Marek <mmarek@suse.cz> | 2010-10-12 15:09:06 +0200 |
commit | 239060b93bb30a4ad55f1ecaa512464a035cc5ba (patch) | |
tree | 77f79810e57d4fc24356eca0cd6db463e8994128 /Documentation/blackfin/bfin-spi-notes.txt | |
parent | 1408b15b98635a13bad2e2a50b3c2ae2ccdf625b (diff) | |
parent | e9203c988234aa512bd45ca32b52e21c7bbfc414 (diff) | |
download | op-kernel-dev-239060b93bb30a4ad55f1ecaa512464a035cc5ba.zip op-kernel-dev-239060b93bb30a4ad55f1ecaa512464a035cc5ba.tar.gz |
Merge branch 'kbuild/rc-fixes' into kbuild/kconfig
We need to revert the temporary hack in 71ebc01, hence the merge.
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 0000000..556fa87 --- /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. |