diff mbox

[1/7] mfd: cros_ec: spi: calculate delay between transfers correctly

Message ID 1397757570-19750-2-git-send-email-dianders@chromium.org (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

Doug Anderson April 17, 2014, 5:59 p.m. UTC 
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>
---
 drivers/mfd/cros_ec_spi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Simon Glass April 18, 2014, 5:27 p.m. UTC | #1 
On 17 April 2014 11:59, Doug Anderson <dianders@chromium.org> wrote:
> 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>
--
To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
diff mbox

Patch

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 */