spi: core: Increase timeout value

The existing timeout value in wait_for_completion_timeout is
calculated from the transfer length and speed with tolerance of 10msec.
This is too low because this is used for error conditions such as
hardware hang etc.
The xfer->speed_hz considered may not be the actual speed set
because the best clock divisor is chosen from a limited set such that
the actual speed <= requested speed. This will lead to timeout being
less than actual transfer time.
Considering acceptable latencies, this timeout can be set to a
value double the expected transfer plus 100 msecs.
This patch adds the same in the core.

Signed-off-by: Harini Katakam <harinik@xilinx.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 4eb9bf02996cf179cf3e6365421867aaf8a10593..f01cbb41e6cad8037df776a5d44efc1d2e2d41ef 100644 (file)
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -775,7 +775,7 @@ static int spi_transfer_one_message(struct spi_master *master,
                if (ret > 0) {
                        ret = 0;
                        ms = xfer->len * 8 * 1000 / xfer->speed_hz;
-                       ms += 10; /* some tolerance */
+                       ms += ms + 100; /* some tolerance */
 
                        ms = wait_for_completion_timeout(&master->xfer_completion,
                                                         msecs_to_jiffies(ms));