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Subject[PATCH] spi: Clarify (a)synchronous transfer_one()
Date
From: Geert Uytterhoeven <geert+renesas@linux-m68k.org>

Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
---
include/linux/spi/spi.h | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 21a7251d85ee..5319a8510921 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -282,10 +282,12 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
* @prepare_message: set up the controller to transfer a single message,
* for example doing DMA mapping. Called from threaded
* context.
- * @transfer_one: transfer a single spi_transfer. When the
- * driver is finished with this transfer it must call
- * spi_finalize_current_transfer() so the subsystem can issue
- * the next transfer
+ * @transfer_one: transfer a single spi_transfer.
+ * Synchronous transfer methods must return 0 on success.
+ * Asynchronous transfer methods must return a strict-positive
+ * value on successful submission, and must call
+ * spi_finalize_current_transfer() when the driver is finished
+ * so the subsystem can issue the next transfer
* @unprepare_message: undo any work done by prepare_message().
* @cs_gpios: Array of GPIOs to use as chip select lines; one per CS
* number. Any individual value may be -ENOENT for CS lines that
--
1.7.9.5


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