iio: dht11: Improve logging

* Unify log messages
* Add more DEBUG messages

Apparently this driver is working unreliably on some platforms that I can't
test. Therefore I want an easy way for bug reporters to provide useful
information without making the driver too chatty by default.

Signed-off-by: Harald Geyer <harald@ccbib.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 34 insertions, 6 deletions

diff --git a/drivers/iio/humidity/dht11.c b/drivers/iio/humidity/dht11.c
index 20b500da94db..9c47bc98f3ac 100644
--- a/drivers/iio/humidity/dht11.c
+++ b/drivers/iio/humidity/dht11.c
@@ -96,6 +96,24 @@ struct dht11 {
         struct {s64 ts; int value; }    edges[DHT11_EDGES_PER_READ];
 };
 
+#ifdef CONFIG_DYNAMIC_DEBUG
+/*
+ * dht11_edges_print: show the data as actually received by the
+ *                    driver.
+ */
+static void dht11_edges_print(struct dht11 *dht11)
+{
+        int i;
+
+        dev_dbg(dht11->dev, "%d edges detected:\n", dht11->num_edges);
+        for (i = 1; i < dht11->num_edges; ++i) {
+                dev_dbg(dht11->dev, "%d: %lld ns %s\n", i,
+                        dht11->edges[i].ts - dht11->edges[i - 1].ts,
+                        dht11->edges[i - 1].value ? "high" : "low");
+        }
+}
+#endif /* CONFIG_DYNAMIC_DEBUG */
+
 static unsigned char dht11_decode_byte(char *bits)
 {
         unsigned char ret = 0;
@@ -119,8 +137,12 @@ static int dht11_decode(struct dht11 *dht11, int offset)
         for (i = 0; i < DHT11_BITS_PER_READ; ++i) {
                 t = dht11->edges[offset + 2 * i + 2].ts -
                         dht11->edges[offset + 2 * i + 1].ts;
-                if (!dht11->edges[offset + 2 * i + 1].value)
-                        return -EIO;  /* lost synchronisation */
+                if (!dht11->edges[offset + 2 * i + 1].value) {
+                        dev_dbg(dht11->dev,
+                                "lost synchronisation at edge %d\n",
+                                offset + 2 * i + 1);
+                        return -EIO;
+                }
                 bits[i] = t > DHT11_THRESHOLD;
         }
 
@@ -130,8 +152,10 @@ static int dht11_decode(struct dht11 *dht11, int offset)
         temp_dec = dht11_decode_byte(&bits[24]);
         checksum = dht11_decode_byte(&bits[32]);
 
-        if (((hum_int + hum_dec + temp_int + temp_dec) & 0xff) != checksum)
+        if (((hum_int + hum_dec + temp_int + temp_dec) & 0xff) != checksum) {
+                dev_dbg(dht11->dev, "invalid checksum\n");
                 return -EIO;
+        }
 
         dht11->timestamp = ktime_get_boot_ns();
         if (hum_int < 20) {  /* DHT22 */
@@ -182,6 +206,7 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
         mutex_lock(&dht11->lock);
         if (dht11->timestamp + DHT11_DATA_VALID_TIME < ktime_get_boot_ns()) {
                 timeres = ktime_get_resolution_ns();
+                dev_dbg(dht11->dev, "current timeresolution: %dns\n", timeres);
                 if (timeres > DHT11_MIN_TIMERES) {
                         dev_err(dht11->dev, "timeresolution %dns too low\n",
                                 timeres);
@@ -219,10 +244,13 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
 
                 free_irq(dht11->irq, iio_dev);
 
+#ifdef CONFIG_DYNAMIC_DEBUG
+                dht11_edges_print(dht11);
+#endif
+
                 if (ret == 0 && dht11->num_edges < DHT11_EDGES_PER_READ - 1) {
-                        dev_err(&iio_dev->dev,
-                                "Only %d signal edges detected\n",
-                                        dht11->num_edges);
+                        dev_err(dht11->dev, "Only %d signal edges detected\n",
+                                dht11->num_edges);
                         ret = -ETIMEDOUT;
                 }
                 if (ret < 0)