Messages in this thread | | | Date | Tue, 28 Feb 2006 14:13:27 +0900 (JST) | Subject | SPI: cs_change usage | From | Atsushi Nemoto <> |
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Hi. Now I'm looking into new SPI subsystem and I have a question.
In spi.h, cs_change's usage is described as follows:
> * (i) If the transfer isn't the last one in the message, this flag is > * used to make the chipselect briefly go inactive in the middle of the > * message. Toggling chipselect in this way may be needed to terminate > * a chip command, letting a single spi_message perform all of group of > * chip transactions together. > * > * (ii) When the transfer is the last one in the message, the chip may > * stay selected until the next transfer. This is purely a performance > * hint; the controller driver may need to select a different device > * for the next message.
I'm confused by the last paragraph. In the last transfer, does "cs_change = 1" mean "keep the chipselect activated" ? Or the paragraph is saying "I can set cs_change to zero to keep the chipselect activated after the message" ?
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