Using counter based retry loops for peripherals results in the delay being significantly overrun during high-load situations where delay functions tend to be vary imprecise and overrun there timeouts. So condition the termination on the actual condition of 2s for the re-calibration to have been successful.
As this is a very long delay there is no advantage in using high-resolution timers thus switching this to msleep(). Signed-off-by: Nicholas Mc Guire <[email protected]> --- Problem detected with coccinelle script (usleep_range for long delay) The basic model for the fix up here is to use timeout = jiffies + (retry_time) do { check() mleep() } while (time_is_after_jiffies(timeout)); rather than using a counter and have very long retry loops under load conditions. In the specific case it is sleep()/check() though to wait on the previous write to complete. The initial intent was to move the usleep_range() to msleep() as the delays are very long - if this refactoring of the timeout loop is desirable or not is not clear (both time and count based models seem to be common). Patch was compile tested with: x86_64_defconfig + CONFIG_MOUSE_CYAPA=m Patch is against 4.10-rc3 (localversion-next is next-20170113) drivers/input/mouse/cyapa_gen3.c | 27 ++++++++++++--------------- 1 file changed, 12 insertions(+), 15 deletions(-) diff --git a/drivers/input/mouse/cyapa_gen3.c b/drivers/input/mouse/cyapa_gen3.c index f9600753..0c544de 100644 --- a/drivers/input/mouse/cyapa_gen3.c +++ b/drivers/input/mouse/cyapa_gen3.c @@ -789,7 +789,7 @@ static ssize_t cyapa_gen3_do_calibrate(struct device *dev, const char *buf, size_t count) { struct cyapa *cyapa = dev_get_drvdata(dev); - int tries; + unsigned long timeout; int ret; ret = cyapa_read_byte(cyapa, CYAPA_CMD_DEV_STATUS); @@ -812,31 +812,28 @@ static ssize_t cyapa_gen3_do_calibrate(struct device *dev, goto out; } - tries = 20; /* max recalibration timeout 2s. */ + /* max recalibration timeout 2s. */ + timeout = jiffies + 20 * HZ; do { /* * For this recalibration, the max time will not exceed 2s. * The average time is approximately 500 - 700 ms, and we * will check the status every 100 - 200ms. */ - usleep_range(100000, 200000); - + msleep(100); ret = cyapa_read_byte(cyapa, CYAPA_CMD_DEV_STATUS); if (ret < 0) { - dev_err(dev, "Error reading dev status: %d\n", - ret); + dev_err(dev, "Error reading dev status: %d\n", ret); goto out; } - if ((ret & CYAPA_DEV_NORMAL) == CYAPA_DEV_NORMAL) - break; - } while (--tries); + if ((ret & CYAPA_DEV_NORMAL) == CYAPA_DEV_NORMAL) { + dev_dbg(dev, "Calibration successful.\n"); + goto out; + } + } while (time_is_after_jiffies(timeout)); - if (tries == 0) { - dev_err(dev, "Failed to calibrate. Timeout.\n"); - ret = -ETIMEDOUT; - goto out; - } - dev_dbg(dev, "Calibration successful.\n"); + dev_err(dev, "Failed to calibrate. Timeout.\n"); + ret = -ETIMEDOUT; out: return ret < 0 ? ret : count; -- 2.1.4
