iio: adc: mcp320x: Speed up readout of single-channel ADCs

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Single-channel converters such as mcp3001, mcp3201, mcp3301 and the
upcoming mcp3550/1/3 lack a MOSI pin, so there's no need to call
mcp320x_channel_to_tx_data() for them.

Moreover, instead of calling spi_read() for these converters, which
generates an spi_message and spi_transfer on the stack on every readout,
it's more efficient to use the spi_message and spi_transfer[] included
in struct mcp320x (as we do for multi-channel ADCs), but initialize the
spi_message only with the receive transfer.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

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Lukas Wunner 2017-09-09 20:32:41 +02:00 • committed by Jonathan Cameron

parent f1f065d7ac

commit ea9103186d

1 changed files with 14 additions and 20 deletions

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drivers/iio/adc/mcp320x.c

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