This is a note to let you know that I've just added the patch titled mfd: cros ec: spi: Don't send first message too soon to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mfd-cros-ec-spi-don-t-send-first-message-too-soon.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 15d8374874ded0bec37ef27f8301a6d54032c0e5 Mon Sep 17 00:00:00 2001 From: Jon Hunter <jonathanh@xxxxxxxxxx> Date: Tue, 14 Nov 2017 14:43:27 +0000 Subject: mfd: cros ec: spi: Don't send first message too soon From: Jon Hunter <jonathanh@xxxxxxxxxx> commit 15d8374874ded0bec37ef27f8301a6d54032c0e5 upstream. 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. Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx> Reviewed-by: Brian Norris <briannorris@xxxxxxxxxxxx> Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx> Acked-by: Benson Leung <bleung@xxxxxxxxxxxx> Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/mfd/cros_ec_spi.c | 1 + 1 file changed, 1 insertion(+) --- 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_ 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) { Patches currently in stable-queue which might be from jonathanh@xxxxxxxxxx are queue-4.14/mfd-cros-ec-spi-don-t-send-first-message-too-soon.patch