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@xxxxxxxxxxxx>
---
drivers/mfd/cros_ec_spi.c | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)
diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
index 0b8d328..0cbc3db 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);
--
2.0.0.526.g5318336
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