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Commit 32d111a9 authored by Alexander E. Patrakov's avatar Alexander E. Patrakov Committed by Mauro Carvalho Chehab
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V4L/DVB (6506): saa7134-alsa: Fix mmap support 



Trent Piepho wrote:
> I do not think the saa7134-alsa driver supports mmap.  The cx88-alsa driver
> also claimed to support mmap, but it never worked until I fixed it.  It's
> pretty clear that the code in saa7134-alsa was based on the same code as
> cx88-alsa, so it's likely it has the same bug.

You are right. The patch below (based on your cx88 patch, but I don't
really understand it) fixes mmap support in saa7134-alsa for me.
Recording via mmap (arecord -M -f S16_LE -c 2 -r 32000 -D hw:1) didn't
work at all before, works now, tested for at least 20 minutes (but,
unfortunately, with one overrun at least 0.719 ms long).

Signed-off-by: default avatarAlexander E. Patrakov <patrakov@ums.usu.ru>
Acked-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarTrent Piepho <xyzzy@speakeasy.org>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@infradead.org>
parent f21daa41

drivers/media/video/saa7134/saa7134-alsa.c

+15 −1
Original line number Diff line number Diff line
@@ -543,8 +543,10 @@ static int snd_card_saa7134_hw_params(struct snd_pcm_substream * substream, 
	   V4L functions, and force ALSA to use that as the DMA area */



	substream->runtime->dma_area = dev->dmasound.dma.vmalloc;

	substream->runtime->dma_bytes = dev->dmasound.bufsize;

	substream->runtime->dma_addr = 0;



	return 1;

	return 0;



}
@@ -651,6 +653,17 @@ static int snd_card_saa7134_capture_open(struct snd_pcm_substream * substream) 
	return 0;

}



/*

 * page callback (needed for mmap)

 */



static struct page *snd_card_saa7134_page(struct snd_pcm_substream *substream,

					unsigned long offset)

{

	void *pageptr = substream->runtime->dma_area + offset;

	return vmalloc_to_page(pageptr);

}



/*

 * ALSA capture callbacks definition

 */
@@ -664,6 +677,7 @@ static struct snd_pcm_ops snd_card_saa7134_capture_ops = { 
	.prepare =		snd_card_saa7134_capture_prepare,

	.trigger =		snd_card_saa7134_capture_trigger,

	.pointer =		snd_card_saa7134_capture_pointer,

	.page =			snd_card_saa7134_page,

};



/*