Commit 96758059 authored Jun 13, 2014 by Doug Anderson Committed by Lee Jones Jul 09, 2014

mfd: cros_ec: spi: Fix end of transfer on devices with no spi-msg-delay

cros_ec_spi makes the assumption that a 0-length message will put the
spi chip select back to normal (non cs_toggle mode). This used to be
the case back on kernel-3.8 on the spi-s3c64xx driver but doesn't
appear to be true anymore. It seems like it was a pretty questionable
assumption to begin with, so let's fix the code to be more robust. We
know that a message with a single 0-length segment _will_ put things
back in order. Change cros_ec_spi to handle this.

This wasn't a problem on the main user of cros_ec_spi upstream (tegra)
because it specified 'google,cros-ec-spi-msg-delay'.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

parent c03842d8

drivers/mfd/cros_ec_spi.c

+7 −11

Original line number	Diff line number	Diff line
		@@ -266,18 +266,14 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev,
		dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
		}

		/* turn off CS */
		spi_message_init(&msg);

		if (ec_spi->end_of_msg_delay) {
		/*
		* Add delay for last transaction, to ensure the rising edge
		* Turn off CS, possibly adding a delay to ensure the rising edge
		* doesn't come too soon after the end of the data.
		*/
		spi_message_init(&msg);
		memset(&trans, 0, sizeof(trans));
		trans.delay_usecs = ec_spi->end_of_msg_delay;
		spi_message_add_tail(&trans, &msg);
		}

		final_ret = spi_sync(ec_spi->spi, &msg);
		ktime_get_ts(&ts);