linux-kernel - Re: [PATCH] ALSA: hda: Fix assign invalid fixed slots pcm numbers to HDA_PCM_TYPE_HDMI in get_empty_pcm

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Message-ID: <s5hk21fvohf.wl-tiwai@suse.de>
Date:   Sun, 03 Sep 2017 16:35:56 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Wang YanQing <udknight@...il.com>
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        fengguang.wu@...el.com
Subject: Re: [PATCH] ALSA: hda: Fix assign invalid fixed slots pcm numbers to HDA_PCM_TYPE_HDMI in get_empty_pcm_device

On Sun, 03 Sep 2017 15:52:31 +0200,
Wang YanQing wrote:
> 
> The length of pcm_dev_bits in hda_bus is SNDRV_PCM_DEVICES,
> and the definiton of SNDRV_PCM_DEVICES is:
> "
>  #if defined(CONFIG_SND_DYNAMIC_MINORS)
>  #define SNDRV_PCM_DEVICES       (SNDRV_OS_MINORS-2)
>  #else
>  #define SNDRV_PCM_DEVICES       8
>  #endif
> "
> 
> So the max valid fixed slots pcm number is 7, and the first
> non-fixed slot is 8.

It's only when CONFIG_SND_DYNAMIC_MINORS=n, and that's already covered
in the code in get_empty_pcm_device().

#ifndef CONFIG_SND_DYNAMIC_MINORS
		if (audio_idx[type][i] >= 8)
   		       	  break;
#endif

For CONFIG_SND_DYNAMIC_MINORS=y, there is no such restriction, thus
the non-fixed slot begins from 10 as in the current code.


thanks,

Takashi

> 
> Signed-off-by: Wang YanQing <udknight@...il.com>
> ---
>  sound/pci/hda/hda_codec.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
> index 3db26c4..df6b57e 100644
> --- a/sound/pci/hda/hda_codec.c
> +++ b/sound/pci/hda/hda_codec.c
> @@ -3118,7 +3118,7 @@ static int get_empty_pcm_device(struct hda_bus *bus, unsigned int type)
>  	static int audio_idx[HDA_PCM_NTYPES][5] = {
>  		[HDA_PCM_TYPE_AUDIO] = { 0, 2, 4, 5, -1 },
>  		[HDA_PCM_TYPE_SPDIF] = { 1, -1 },
> -		[HDA_PCM_TYPE_HDMI]  = { 3, 7, 8, 9, -1 },
> +		[HDA_PCM_TYPE_HDMI]  = { 3, 7, -1 },
>  		[HDA_PCM_TYPE_MODEM] = { 6, -1 },
>  	};
>  	int i;
> @@ -3139,7 +3139,7 @@ static int get_empty_pcm_device(struct hda_bus *bus, unsigned int type)
>  
>  #ifdef CONFIG_SND_DYNAMIC_MINORS
>  	/* non-fixed slots starting from 10 */
> -	for (i = 10; i < 32; i++) {
> +	for (i = 8; i < 32; i++) {
>  		if (!test_and_set_bit(i, bus->pcm_dev_bits))
>  			return i;
>  	}
> -- 
> 1.8.5.6.2.g3d8a54e.dirty
>