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Commit 86ef3f78 authored by Hans de Goede's avatar Hans de Goede Committed by Mauro Carvalho Chehab
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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: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 8e2ce73e

drivers/media/radio/si470x/radio-si470x-common.c

+6 −4
Original line number Diff line number Diff line
@@ -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;



	if (!radio->status_rssi_auto_update) {

		retval = si470x_get_register(radio, STATUSRSSI);

		if (retval < 0)

			return retval;

	}



	/* driver constants */

	strcpy(tuner->name, "FM");

drivers/media/radio/si470x/radio-si470x-usb.c

+9 −3
Original line number Diff line number Diff line
@@ -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 @@ static void si470x_int_in_callback(struct urb *urb) 
			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;

}

drivers/media/radio/si470x/radio-si470x.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */