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authorDoug Anderson <dianders@chromium.org>2014-06-13 11:13:32 -0700
committerLee Jones <lee.jones@linaro.org>2014-07-09 14:58:00 +0100
commit967580598f46997ce5eeeea812686f5220bb49de (patch)
treedd21d96eacae8420d255b1360cead990b47a5e95 /drivers/mfd/cros_ec_spi.c
parentc03842d89b769db44be5cb0b1ebb384ccfa25f7f (diff)
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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>
Diffstat (limited to 'drivers/mfd/cros_ec_spi.c')
-rw-r--r--drivers/mfd/cros_ec_spi.c18
1 files changed, 7 insertions, 11 deletions
diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
index 0b8d32829166..0cbc3dbeb37f 100644
--- a/drivers/mfd/cros_ec_spi.c
+++ b/drivers/mfd/cros_ec_spi.c
@@ -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 */
+ /*
+ * 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);
-
- if (ec_spi->end_of_msg_delay) {
- /*
- * Add delay for last transaction, to ensure the rising edge
- * doesn't come too soon after the end of the data.
- */
- memset(&trans, 0, sizeof(trans));
- trans.delay_usecs = ec_spi->end_of_msg_delay;
- spi_message_add_tail(&trans, &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);