drivers/leds/leds-lp5523.c: adjust delays and add comments to them
Delays were little bit too long. Adjust delay times and add some comments
to them.
Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/leds/leds-lp5523.c b/drivers/leds/leds-lp5523.c
index 053e1f8..4248d78 100644
--- a/drivers/leds/leds-lp5523.c
+++ b/drivers/leds/leds-lp5523.c
@@ -205,11 +205,14 @@
lp5523_write(client, LP5523_REG_RESET, 0xff);
- usleep_range(10000, 100000);
+ usleep_range(10000, 20000); /*
+ * Exact value is not available. 10 - 20ms
+ * appears to be enough for reset.
+ */
ret |= lp5523_write(client, LP5523_REG_ENABLE, LP5523_ENABLE);
- /* Chip startup time after reset is 500 us */
- usleep_range(1000, 10000);
+ /* Chip startup time is 500 us, 1 - 2 ms gives some margin */
+ usleep_range(1000, 2000);
ret |= lp5523_write(client, LP5523_REG_CONFIG,
LP5523_AUTO_INC | LP5523_PWR_SAVE |
@@ -246,8 +249,8 @@
return -1;
}
- /* Wait 3ms and check the engine status */
- usleep_range(3000, 20000);
+ /* Let the programs run for couple of ms and check the engine status */
+ usleep_range(3000, 6000);
lp5523_read(client, LP5523_REG_STATUS, &status);
status &= LP5523_ENG_STATUS_MASK;
@@ -452,10 +455,10 @@
/* Measure VDD (i.e. VBAT) first (channel 16 corresponds to VDD) */
lp5523_write(chip->client, LP5523_REG_LED_TEST_CTRL,
LP5523_EN_LEDTEST | 16);
- usleep_range(3000, 10000);
+ usleep_range(3000, 6000); /* ADC conversion time is typically 2.7 ms */
ret = lp5523_read(chip->client, LP5523_REG_STATUS, &status);
if (!(status & LP5523_LEDTEST_DONE))
- usleep_range(3000, 10000);
+ usleep_range(3000, 6000); /* Was not ready. Wait little bit */
ret |= lp5523_read(chip->client, LP5523_REG_LED_TEST_ADC, &vdd);
vdd--; /* There may be some fluctuation in measurement */
@@ -471,16 +474,16 @@
chip->pdata->led_config[i].led_current);
lp5523_write(chip->client, LP5523_REG_LED_PWM_BASE + i, 0xff);
- /* let current stabilize 2ms before measurements start */
- usleep_range(2000, 10000);
+ /* let current stabilize 2 - 4ms before measurements start */
+ usleep_range(2000, 4000);
lp5523_write(chip->client,
LP5523_REG_LED_TEST_CTRL,
LP5523_EN_LEDTEST | i);
- /* ledtest takes 2.7ms */
- usleep_range(3000, 10000);
+ /* ADC conversion time is 2.7 ms typically */
+ usleep_range(3000, 6000);
ret = lp5523_read(chip->client, LP5523_REG_STATUS, &status);
if (!(status & LP5523_LEDTEST_DONE))
- usleep_range(3000, 10000);
+ usleep_range(3000, 6000);/* Was not ready. Wait. */
ret |= lp5523_read(chip->client, LP5523_REG_LED_TEST_ADC, &adc);
if (adc >= vdd || adc < LP5523_ADC_SHORTCIRC_LIM)
@@ -933,9 +936,9 @@
if (pdata->enable) {
pdata->enable(0);
- usleep_range(1000, 10000);
+ usleep_range(1000, 2000); /* Keep enable down at least 1ms */
pdata->enable(1);
- usleep_range(1000, 10000); /* Spec says min 500us */
+ usleep_range(1000, 2000); /* 500us abs min. */
}
ret = lp5523_detect(client);