lkml.org 
[lkml]   [2019]   [Sep]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH v2 2/3] 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>
---
drivers/iio/adc/hx711.c | 23 +++++------------------
1 file changed, 5 insertions(+), 18 deletions(-)

diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index 0678964dbd21..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;
@@ -100,7 +101,6 @@ struct hx711_data {

static int hx711_cycle(struct hx711_data *hx711_data)
{
- int val;
unsigned long flags;

/*
@@ -186,8 +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) {
/*
@@ -203,22 +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;
--
2.11.0
\
 
 \ /
  Last update: 2019-09-09 14:38    [W:0.052 / U:7.336 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site