Commit c7a13264 authored by Jussi Laako's avatar Jussi Laako Committed by Takashi Iwai
Browse files

ALSA: usb-audio: Expose sample resolution through proc interface 



At least some USB devices use (MSB-aligned) audio format larger
than the actual resolution of the device. In order to expose the
actual device resolution (bBitResolution), add extra field to the
procfs stream info interface.

Signed-off-by: default avatarJussi Laako <jussi@sonarnerd.net>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent a06702ca

sound/usb/card.h

+1 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ struct audioformat { 
	u64 formats;			/* ALSA format bits */

	unsigned int channels;		/* # channels */

	unsigned int fmt_type;		/* USB audio format type (1-3) */

	unsigned int fmt_bits;		/* number of significant bits */

	unsigned int frame_size;	/* samples per frame for non-audio */

	int iface;			/* interface number */

	unsigned char altsetting;	/* corresponding alternate setting */

sound/usb/format.c

+2 −0
Original line number Diff line number Diff line
@@ -87,6 +87,8 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip, 
	}

	}



	fp->fmt_bits = sample_width;



	if ((pcm_formats == 0) &&

	    (format == 0 || format == (1 << UAC_FORMAT_TYPE_I_UNDEFINED))) {

		/* some devices don't define this correctly... */

sound/usb/proc.c

+1 −0
Original line number Diff line number Diff line
@@ -109,6 +109,7 @@ static void proc_dump_substream_formats(struct snd_usb_substream *subs, struct s 
		if (subs->speed != USB_SPEED_FULL)

			snd_iprintf(buffer, "    Data packet interval: %d us\n",

				    125 * (1 << fp->datainterval));

		snd_iprintf(buffer, "    Bits: %d\n", fp->fmt_bits);

		// snd_iprintf(buffer, "    Max Packet Size = %d\n", fp->maxpacksize);

		// snd_iprintf(buffer, "    EP Attribute = %#x\n", fp->attributes);

	}

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