[alsa-devel] [PATCH 1/1] ALSA: CA0132 - Ensure SCP packet is little-endian format

[Takashi Iwai]

At Wed, 26 Sep 2012 18:23:59 -0700,
Ian Minett wrote:
> 
> From: Ian Minett <ian_minett at creativelabs.com>
> 
> Hi Takashi,
> Great - good to hear the previous DSP loader patches are now living in the 
> hda-ca0132-dsp branch. This patch is based on that branch, and addresses 
> the SCP packet endianness.
> 
> >> The firmware does need to be reloaded when the chip loses power, so it 
> >> doesn't survive S3.
> >OK, we need suspend/resume hooks, too.
> 
> Do we need to do anything specific to handle this? The firmware is already 
> restored upon S3 by the current caching code.

Then it's OK.  I didn't check that the firmware loader gets called in
the resume path in patch_ca0132.c.

Looking at the patch now...:


> Thanks,
> - Ian
> 
> ---
> 
> The DSP firmware expects the SCP data to be in little-endian
> format regardless of the host architecture.
> 
> Signed-off-by: Ian Minett <ian_minett at creativelabs.com>
> 
> ---
> diff --git a/sound/pci/hda/patch_ca0132.c b/sound/pci/hda/patch_ca0132.c
> index 2fd3121..4d7cda4 100644
> --- a/sound/pci/hda/patch_ca0132.c
> +++ b/sound/pci/hda/patch_ca0132.c
> @@ -28,6 +28,7 @@
>  #include <linux/mutex.h>
>  #include <linux/module.h>
>  #include <linux/firmware.h>
> +#include <asm/unaligned.h>
>  #include <sound/core.h>
>  #include "hda_codec.h"
>  #include "hda_local.h"
> @@ -701,9 +702,13 @@ static int dspio_send(struct hda_codec *codec, unsigned int reg,
>  	unsigned int res;
>  	int retry = 50;
>  
> +	/* Handling for Big Endian machine */
> +	unsigned int val;
> +	put_unaligned_le32(data, &val);
> +
>  	/* send bits of data specified by reg to dsp */
>  	do {
> -		res = snd_hda_codec_read(codec, WIDGET_DSP_CTRL, 0, reg, data);
> +		res = snd_hda_codec_read(codec, WIDGET_DSP_CTRL, 0, reg, val);
>  		if ((res >= 0) && (res != VENDOR_STATUS_DSPIO_BUSY))
>  			return res;
>  	} while (--retry);

I don't think this is the right place to fix the endianness.
The value passed to this function should be already in a right order.
The wrong endian value should be corrected at the place where you read
the value.


thanks,

Takashi