'\" t
.\"     Title: spi_sync
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: May 2018
.\"    Manual: Serial Peripheral Interface (SPI)
.\"    Source: Kernel Hackers Manual 3.16.56
.\"  Language: English
.\"
.TH "SPI_SYNC" "9" "May 2018" "Kernel Hackers Manual 3\&.16\&" "Serial Peripheral Interface (S"
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.SH "NAME"
spi_sync \- blocking/synchronous SPI data transfers
.SH "SYNOPSIS"
.HP \w'int\ spi_sync('u
.BI "int spi_sync(struct\ spi_device\ *\ " "spi" ", struct\ spi_message\ *\ " "message" ");"
.SH "ARGUMENTS"
.PP
\fIspi\fR
.RS 4
device with which data will be exchanged
.RE
.PP
\fImessage\fR
.RS 4
describes the data transfers
.RE
.SH "CONTEXT"
.PP
can sleep
.SH "DESCRIPTION"
.PP
This call may only be used from a context that may sleep\&. The sleep is non\-interruptible, and has no timeout\&. Low\-overhead controller drivers may DMA directly into and out of the message buffers\&.
.PP
Note that the SPI device\*(Aqs chip select is active during the message, and then is normally disabled between messages\&. Drivers for some frequently\-used devices may want to minimize costs of selecting a chip, by leaving it selected in anticipation that the next message will go to the same chip\&. (That may increase power usage\&.)
.PP
Also, the caller is guaranteeing that the memory associated with the message will not be freed before this call returns\&.
.PP
It returns zero on success, else a negative error code\&.
.SH "COPYRIGHT"
.br