diff options
| author | Doug Anderson <dianders@chromium.org> | 2014-06-13 11:13:32 -0700 |
|---|---|---|
| committer | Lee Jones <lee.jones@linaro.org> | 2014-07-09 14:58:00 +0100 |
| commit | 967580598f46997ce5eeeea812686f5220bb49de (patch) | |
| tree | dd21d96eacae8420d255b1360cead990b47a5e95 /drivers | |
| parent | c03842d89b769db44be5cb0b1ebb384ccfa25f7f (diff) | |
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')
| -rw-r--r-- | drivers/mfd/cros_ec_spi.c | 18 |
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); |