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mfd: cros_ec: Delay for 50ms when we see EC_CMD_REBOOT_EC

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If someone sends a EC_CMD_REBOOT_EC to the EC, the EC will likely be
unresponsive for quite a while.  Add a delay to the end of the command
to prevent random failures of future commands.

NOTES:
* This could be optimized a bit by simply delaying the next command
  sent, but EC_CMD_REBOOT_EC is such a rare command that the extra
  complexity doesn't seem worth it.
* This is a bit of an "ugly hack" since the SPI driver is effectively
  snooping on the communication and making a lot of assumptions.  It
  would be nice to architect in some better solution long term.
* This same logic probably needs to be applied to the i2c driver.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Doug Anderson 2014-09-18 17:18:54 +02:00 committed by Lee Jones
parent 48b490d23e
commit 659e142be0
1 changed files with 9 additions and 0 deletions
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9
drivers/mfd/cros_ec_spi.c
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@ -65,6 +65,12 @@
*/
#define EC_SPI_RECOVERY_TIME_NS (200 * 1000)
/*
* The EC is unresponsive for a time after a reboot command. Add a
* simple delay to make sure that the bus stays locked.
*/
#define EC_REBOOT_DELAY_MS 50
/**
* struct cros_ec_spi - information about a SPI-connected EC
*
@ -318,6 +324,9 @@ static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
ret = len;
exit:
if (ec_msg->command == EC_CMD_REBOOT_EC)
msleep(EC_REBOOT_DELAY_MS);
mutex_unlock(&ec_spi->lock);
return ret;
}