diff options
| author | Jon Hunter <jonathanh@nvidia.com> | 2017-11-14 14:43:27 +0000 |
|---|---|---|
| committer | Lee Jones <lee.jones@linaro.org> | 2017-11-29 16:28:23 +0000 |
| commit | 15d8374874ded0bec37ef27f8301a6d54032c0e5 (patch) | |
| tree | 13063d2045d6479d3ecbe8d5c1fc373bdde813c1 /drivers/mfd | |
| parent | 4fbd8d194f06c8a3fd2af1ce560ddb31f7ec8323 (diff) | |
| download | lwn-15d8374874ded0bec37ef27f8301a6d54032c0e5.tar.gz lwn-15d8374874ded0bec37ef27f8301a6d54032c0e5.zip | |
mfd: cros ec: spi: Don't send first message too soon
On the Tegra124 Nyan-Big chromebook the very first SPI message sent to
the EC is failing.
The Tegra SPI driver configures the SPI chip-selects to be active-high
by default (and always has for many years). The EC SPI requires an
active-low chip-select and so the Tegra chip-select is reconfigured to
be active-low when the EC SPI driver calls spi_setup(). The problem is
that if the first SPI message to the EC is sent too soon after
reconfiguring the SPI chip-select, it fails.
The EC SPI driver prevents back-to-back SPI messages being sent too
soon by keeping track of the time the last transfer was sent via the
variable 'last_transfer_ns'. To prevent the very first transfer being
sent too soon, initialise the 'last_transfer_ns' variable after calling
spi_setup() and before sending the first SPI message.
Cc: <stable@vger.kernel.org>
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Diffstat (limited to 'drivers/mfd')
| -rw-r--r-- | drivers/mfd/cros_ec_spi.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c index c9714072e224..a14196e95e9b 100644 --- a/drivers/mfd/cros_ec_spi.c +++ b/drivers/mfd/cros_ec_spi.c @@ -667,6 +667,7 @@ static int cros_ec_spi_probe(struct spi_device *spi) sizeof(struct ec_response_get_protocol_info); ec_dev->dout_size = sizeof(struct ec_host_request); + ec_spi->last_transfer_ns = ktime_get_ns(); err = cros_ec_register(ec_dev); if (err) { |