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| author | Mark Brown <broonie@opensource.wolfsonmicro.com> | 2009-05-05 13:12:55 +0400 |
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| committer | Mark Brown <broonie@opensource.wolfsonmicro.com> | 2009-05-05 13:12:55 +0400 |
| commit | f3831a592fe4332a70baad64a860b345398885b7 (patch) | |
| tree | fd27b986295fe5a4f1c0924a804228f829a4c894 /Documentation/spi/spi-summary | |
| parent | 376f7839b72ec526173cafb5d8eadfc61e2effdf (diff) | |
| parent | 8560b9321f9050968f393ce1ec67e47c1a0bd5cf (diff) | |
| download | linux-f3831a592fe4332a70baad64a860b345398885b7.tar.xz | |
Merge commit 'takashi/topic/asoc' into for-2.6.31
Diffstat (limited to 'Documentation/spi/spi-summary')
| -rw-r--r-- | Documentation/spi/spi-summary | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/spi/spi-summary b/Documentation/spi/spi-summary index 0f5122eb282b..4a02d2508bc8 100644 --- a/Documentation/spi/spi-summary +++ b/Documentation/spi/spi-summary @@ -511,10 +511,16 @@ SPI MASTER METHODS This sets up the device clock rate, SPI mode, and word sizes. Drivers may change the defaults provided by board_info, and then call spi_setup(spi) to invoke this routine. It may sleep. + Unless each SPI slave has its own configuration registers, don't change them right away ... otherwise drivers could corrupt I/O that's in progress for other SPI devices. + ** BUG ALERT: for some reason the first version of + ** many spi_master drivers seems to get this wrong. + ** When you code setup(), ASSUME that the controller + ** is actively processing transfers for another device. + master->transfer(struct spi_device *spi, struct spi_message *message) This must not sleep. Its responsibility is arrange that the transfer happens and its complete() callback is issued. The two |