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authorAndreas Klinger <ak@it-klinger.de>2019-09-09 14:37:48 +0200
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2019-10-22 12:58:07 +0100
commit68d8ab3cf1a98e9d296221afdb6433715fd57535 (patch)
tree475034390dbcbf1afdef5b6ce0c2d9301def02d9 /drivers/iio
parent1cd92d42dbfff03bdd209fd6ccd5aec395faa915 (diff)
downloadlinux-68d8ab3cf1a98e9d296221afdb6433715fd57535.tar.bz2
iio: adc: hx711: optimize performance in read cycle
Set gain in hx711_reset() to its default value after a reset cycle. This omits one precautionary read cycle, because the read is performed in hx711_set_gain_for_channel() anyway if gain has changed. Check for DOUT low and if its high wait some time if it goes down instead of doing a blind reset cycle when DOUT is not down. This is a performance optimization which allows to query the sensor with a higher frequency. Signed-off-by: Andreas Klinger <ak@it-klinger.de> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Diffstat (limited to 'drivers/iio')
-rw-r--r--drivers/iio/adc/hx711.c22
1 files changed, 5 insertions, 17 deletions
diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index 62e6c8badd22..c8686558429b 100644
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -23,6 +23,7 @@
/* gain to pulse and scale conversion */
#define HX711_GAIN_MAX 3
+#define HX711_RESET_GAIN 128
struct hx711_gain_to_scale {
int gain;
@@ -185,8 +186,7 @@ static int hx711_wait_for_ready(struct hx711_data *hx711_data)
static int hx711_reset(struct hx711_data *hx711_data)
{
- int ret;
- int val = gpiod_get_value(hx711_data->gpiod_dout);
+ int val = hx711_wait_for_ready(hx711_data);
if (val) {
/*
@@ -202,22 +202,10 @@ static int hx711_reset(struct hx711_data *hx711_data)
msleep(10);
gpiod_set_value(hx711_data->gpiod_pd_sck, 0);
- ret = hx711_wait_for_ready(hx711_data);
- if (ret)
- return ret;
- /*
- * after a reset the gain is 128 so we do a dummy read
- * to set the gain for the next read
- */
- ret = hx711_read(hx711_data);
- if (ret < 0)
- return ret;
-
- /*
- * after a dummy read we need to wait vor readiness
- * for not mixing gain pulses with the clock
- */
val = hx711_wait_for_ready(hx711_data);
+
+ /* after a reset the gain is 128 */
+ hx711_data->gain_set = HX711_RESET_GAIN;
}
return val;