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mfd: cros_ec: spi: Make the cros_ec_spi timeout more reliable

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The cros_ec_spi transfer had two problems with its timeout code:

1. It looked at the timeout even in the case that it found valid data.
2. If the cros_ec_spi code got switched out for a while, it's possible
   it could get a timeout after a single loop.  Let's be paranoid and
   make sure we do one last transfer after the timeout expires.

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>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Doug Anderson 2014-04-30 10:44:06 -07:00 committed by Lee Jones
parent 362196e5d0
commit c9a81d67ce
1 changed files with 12 additions and 3 deletions
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15
drivers/mfd/cros_ec_spi.c
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@ -113,7 +113,9 @@ static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
/* Receive data until we see the header byte */ /* Receive data until we see the header byte */
deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS); deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS);
do { while (true) {
unsigned long start_jiffies = jiffies;
memset(&trans, 0, sizeof(trans)); memset(&trans, 0, sizeof(trans));
trans.cs_change = 1; trans.cs_change = 1;
trans.rx_buf = ptr = ec_dev->din; trans.rx_buf = ptr = ec_dev->din;
@ -134,12 +136,19 @@ static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
break; break;
} }
} }
if (ptr != end)
break;
if (time_after(jiffies, deadline)) { /*
* Use the time at the start of the loop as a timeout. This
* gives us one last shot at getting the transfer and is useful
* in case we got context switched out for a while.
*/
if (time_after(start_jiffies, deadline)) {
dev_warn(ec_dev->dev, "EC failed to respond in time\n"); dev_warn(ec_dev->dev, "EC failed to respond in time\n");
return -ETIMEDOUT; return -ETIMEDOUT;
} }
} while (ptr == end); }
/* /*
* ptr now points to the header byte. Copy any valid data to the * ptr now points to the header byte. Copy any valid data to the