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Subject[PATCH v2 1/7] mfd: cros_ec: spi: calculate delay between transfers correctly
Date
From: David Hendricks <dhendrix@chromium.org>

To avoid spamming the EC we calculate the time between the previous
transfer and the current transfer and force a delay if the time delta
is too small.

However, a small miscalculation causes the delay period to be
far too short. Most noticably this impacts commands with a long
turnaround time such as EC firmware reads and writes.

Signed-off-by: David Hendricks <dhendrix@chromium.org>
Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Andrew Bresticker <abrestic@chromium.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
---
Changes in v2: None

drivers/mfd/cros_ec_spi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
index 84af8d7..c185eb6 100644
--- a/drivers/mfd/cros_ec_spi.c
+++ b/drivers/mfd/cros_ec_spi.c
@@ -219,7 +219,7 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev,
ktime_get_ts(&ts);
delay = timespec_to_ns(&ts) - ec_spi->last_transfer_ns;
if (delay < EC_SPI_RECOVERY_TIME_NS)
- ndelay(delay);
+ ndelay(EC_SPI_RECOVERY_TIME_NS - delay);
}

/* Transmit phase - send our message */
--
1.9.1.423.g4596e3a


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