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Date: Wed, 30 Apr 2014 10:44:06 -0700 From: Doug Anderson <dianders@...omium.org> To: lee.jones@...aro.org, swarren@...dia.com, wsa@...-dreams.de Cc: abrestic@...omium.org, dgreid@...omium.org, olof@...om.net, sjg@...omium.org, linux-samsung-soc@...r.kernel.org, linux-tegra@...r.kernel.org, Doug Anderson <dianders@...omium.org>, sameo@...ux.intel.com, linux-kernel@...r.kernel.org Subject: [PATCH v3 3/7] mfd: cros_ec: spi: Make the cros_ec_spi timeout more reliable 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@...omium.org> Acked-by: Lee Jones <lee.jones@...aro.org> Reviewed-by: Simon Glass <sjg@...omium.org> Tested-by: Andrew Bresticker <abrestic@...omium.org> Tested-by: Stephen Warren <swarren@...dia.com> --- Changes in v3: None Changes in v2: None drivers/mfd/cros_ec_spi.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c index a2a605d..4f863c3 100644 --- a/drivers/mfd/cros_ec_spi.c +++ b/drivers/mfd/cros_ec_spi.c @@ -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 */ deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS); - do { + while (true) { + unsigned long start_jiffies = jiffies; + memset(&trans, 0, sizeof(trans)); trans.cs_change = 1; 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; } } + 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"); return -ETIMEDOUT; } - } while (ptr == end); + } /* * ptr now points to the header byte. Copy any valid data to the -- 1.9.1.423.g4596e3a -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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