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author | Michal Marek <mmarek@suse.cz> | 2010-10-28 00:15:57 +0200 |
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committer | Michal Marek <mmarek@suse.cz> | 2010-10-28 00:15:57 +0200 |
commit | b74b953b998bcc2db91b694446f3a2619ec32de6 (patch) | |
tree | 6ce24caabd730f6ae9287ed0676ec32e6ff31e9d /Documentation/blackfin/bfin-spi-notes.txt | |
parent | scripts/namespace.pl: improve to get more correct results (diff) | |
parent | Linux 2.6.36 (diff) | |
download | linux-b74b953b998bcc2db91b694446f3a2619ec32de6.tar.xz linux-b74b953b998bcc2db91b694446f3a2619ec32de6.zip |
Merge commit 'v2.6.36' into kbuild/misc
Update to be able to fix a recent change to scripts/basic/docproc.c
(commit eda603f).
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. |