Re: [PATCH v4 1/5] mfd: cros_ec: Delay for 50ms when we see EC_CMD_REBOOT_EC
From: Lee Jones <hidden>
Date: 2014-09-29 07:49:21
Also in:
linux-i2c, linux-samsung-soc
On Thu, 18 Sep 2014, Javier Martinez Canillas wrote:
From: Doug Anderson <dianders@chromium.org> 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 <redacted> Reviewed-by: Vadim Bendebury <redacted> Signed-off-by: Javier Martinez Canillas <redacted> Acked-by: Lee Jones <redacted> --- drivers/mfd/cros_ec_spi.c | 9 +++++++++ 1 file changed, 9 insertions(+)
Applied, thanks.
quoted hunk ↗ jump to hunk
diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c index 588c700..b396705 100644 --- a/drivers/mfd/cros_ec_spi.c +++ b/drivers/mfd/cros_ec_spi.c@@ -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; }
-- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog