> 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(-)
Looks fine to me and I'm sure you've tested this on your platform.
Applied, thanks.
> 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);
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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