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author | Takashi Iwai <tiwai@suse.de> | 2010-08-18 15:17:30 +0200 |
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committer | Takashi Iwai <tiwai@suse.de> | 2010-08-18 15:17:30 +0200 |
commit | 6ab561c8aab2e4af535f09adbc6253f958536848 (patch) | |
tree | 37846adb4ea106485720d113e252d71d615c23ed /Documentation/blackfin/bfin-spi-notes.txt | |
parent | 4f4e8f69895c8696a4bcc751817d4b186023ac44 (diff) | |
parent | cbaa9f60d5d5c3af10f94e0d49789d5b82341a4a (diff) | |
download | linux-6ab561c8aab2e4af535f09adbc6253f958536848.tar.gz linux-6ab561c8aab2e4af535f09adbc6253f958536848.tar.bz2 linux-6ab561c8aab2e4af535f09adbc6253f958536848.zip |
Merge branch 'topic/isa' into topic/misc
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. |