Commit 218e0b57 authored Jan 05, 2016 by Marcus Weseloh Committed by Mark Brown Jan 07, 2016

spi: sun4i: Prevent chip-select from being activated twice before a transfer



The SPI core calls set_cs before a transfer, but the SUN4I_CTL_CS_MANUAL
flag is only set in transfer_one. This leads to the following pattern on
the chip-select line (with runtime power-management on every transfer,
without it only on the first one):

activate, deactivate, activate, transfer, deactivate

Moving the configuration of the SUN4I_CTL_CS_MANUAL flag from transfer_one
to set_cs removes the double activation.

Signed-off-by: Marcus Weseloh <mweseloh42@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

parent 8005c49d

drivers/spi/spi-sun4i.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -140,6 +140,9 @@ static void sun4i_spi_set_cs(struct spi_device *spi, bool enable)
		reg &= ~SUN4I_CTL_CS_MASK;
		reg \|= SUN4I_CTL_CS(spi->chip_select);

		/* We want to control the chip select manually */
		reg \|= SUN4I_CTL_CS_MANUAL;

		if (enable)
		reg \|= SUN4I_CTL_CS_LEVEL;
		else
		@@ -222,9 +225,6 @@ static int sun4i_spi_transfer_one(struct spi_master *master,
		else
		reg \|= SUN4I_CTL_DHB;

		/* We want to control the chip select manually */
		reg \|= SUN4I_CTL_CS_MANUAL;

		sun4i_spi_write(sspi, SUN4I_CTL_REG, reg);

		/* Ensure that we have a parent clock fast enough */

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