Reading registers from the pcear USB dongles with the si470x causes a
loud pop (and an alsa buffer overrun). Since most radio apps periodically
call G_TUNER to update mono/stereo, signal and afc status this leads
to the music . pop . music . pop . music -> not good.
On the internet there is an howto for flashing the pcear with a newer
firmware from the silabs reference boardto fix this, but:
1) This howto relies on a special version of the driver which allows
firmware flashing
2) We should try to avoid the answer to a bug report being upgrade your
firmware, if at all possible
3) Windows does not suffer from the pop sounds
After a quick look at the driver I found at that the register reads are
not necessary at all, as the device gives us the necessary status through
usb interrupt packets, and the driver already uses these!
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/media/radio/si470x/radio-si470x-common.c | 10 ++++++----
drivers/media/radio/si470x/radio-si470x-usb.c | 12 +++++++++---
drivers/media/radio/si470x/radio-si470x.h | 1 +
3 files changed, 16 insertions(+), 7 deletions(-)
diff --git a/drivers/media/radio/si470x/radio-si470x-common.c b/drivers/media/radio/si470x/radio-si470x-common.c
index d485b79..5dbb897 100644
--- a/drivers/media/radio/si470x/radio-si470x-common.c
+++ b/drivers/media/radio/si470x/radio-si470x-common.c
@@ -583,14 +583,16 @@ static int si470x_vidioc_g_tuner(struct file *file, void *priv,
struct v4l2_tuner *tuner)
{
struct si470x_device *radio = video_drvdata(file);
- int retval;
+ int retval = 0;
if (tuner->index != 0)
return -EINVAL;
- retval = si470x_get_register(radio, STATUSRSSI);
- if (retval < 0)
- return retval;
+ if (!radio->status_rssi_auto_update) {
+ retval = si470x_get_register(radio, STATUSRSSI);
+ if (retval < 0)
+ return retval;
+ }
/* driver constants */
strcpy(tuner->name, "FM");
diff --git a/drivers/media/radio/si470x/radio-si470x-usb.c b/drivers/media/radio/si470x/radio-si470x-usb.c
index f412f7a..0da5c98 100644
--- a/drivers/media/radio/si470x/radio-si470x-usb.c
+++ b/drivers/media/radio/si470x/radio-si470x-usb.c
@@ -399,12 +399,16 @@ static void si470x_int_in_callback(struct urb *urb)
}
}
- if ((radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS) == 0)
+ /* Sometimes the device returns len 0 packets */
+ if (urb->actual_length != RDS_REPORT_SIZE)
goto resubmit;
- if (urb->actual_length > 0) {
+ radio->registers[STATUSRSSI] =
+ get_unaligned_be16(&radio->int_in_buffer[1]);
+
+ if ((radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS)) {
/* Update RDS registers with URB data */
- for (regnr = 0; regnr < RDS_REGISTER_NUM; regnr++)
+ for (regnr = 1; regnr < RDS_REGISTER_NUM; regnr++)
radio->registers[STATUSRSSI + regnr] =
get_unaligned_be16(&radio->int_in_buffer[
regnr * RADIO_REGISTER_SIZE + 1]);
@@ -480,6 +484,7 @@ resubmit:
radio->int_in_running = 0;
}
}
+ radio->status_rssi_auto_update = radio->int_in_running;
}
@@ -560,6 +565,7 @@ static int si470x_start_usb(struct si470x_device *radio)
"submitting int urb failed (%d)\n", retval);
radio->int_in_running = 0;
}
+ radio->status_rssi_auto_update = radio->int_in_running;
return retval;
}
diff --git a/drivers/media/radio/si470x/radio-si470x.h b/drivers/media/radio/si470x/radio-si470x.h
index 4921cab..2a0a46f 100644
--- a/drivers/media/radio/si470x/radio-si470x.h
+++ b/drivers/media/radio/si470x/radio-si470x.h
@@ -161,6 +161,7 @@ struct si470x_device {
struct completion completion;
bool stci_enabled; /* Seek/Tune Complete Interrupt */
+ bool status_rssi_auto_update; /* Does RSSI get updated automatic? */
#if defined(CONFIG_USB_SI470X) || defined(CONFIG_USB_SI470X_MODULE)
/* reference to USB and video device */
--
1.7.10.2
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