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[media] radio-si470x: Don't unnecesarily read registers on G_TUNER 

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@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans de Goede 2012-06-14 09:43:11 -03:00 committed by Mauro Carvalho Chehab
parent 8e2ce73e93
commit 86ef3f78b8
3 changed files with 16 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/media/radio/si470x/radio-si470x-common.c
View File

@ -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");

12
drivers/media/radio/si470x/radio-si470x-usb.c
View File

@ -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;
}

1
drivers/media/radio/si470x/radio-si470x.h
View File

@ -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 */