[alsa-devel] [PATCH] snd-core: enlarge snd_card.components for up to 4 codecs

[Takashi Iwai]

At Tue, 7 Oct 2008 16:34:29 +0800,
Wu Fengguang wrote:
> 
> On Tue, Oct 07, 2008 at 10:10:43AM +0200, Takashi Iwai wrote:
> > At Tue, 7 Oct 2008 14:56:06 +0800,
> > Wu Fengguang wrote:
> > > 
> > > Enlarge snd_card.components[80] to 128 bytes, with space for 4 codecs.
> > > The previous size 80 cannot support HP 2230s which has 3 codecs.
> > > 
> > > Signed-off-by: Wu Fengguang <wfg at linux.intel.com>
> > 
> > Thanks for the patch.  Unfortunately, this can't be applied as is.
> > struct snd_ctl_card_info is exported and used as the ioctl parameter,
> > thus you cannot change the size.
> > 
> > One possible fix is to merge reserved[48] into components[80]
> > so that the struct size is kept as is.
> > But still we have to be very careful to such a change, and need to
> > investigate all possible places to refer it.
> 
> OK.
> 
> FYI, this is the debug patch and kernel message(lookout the first line) on HP 2230s:
> 
> diff --git a/sound/core/init.c b/sound/core/init.c
> index 8af467d..704d7e8 100644
> --- a/sound/core/init.c
> +++ b/sound/core/init.c
> @@ -706,6 +706,8 @@ int snd_component_add(struct snd_card *card, const char *component)
>  			return 1;
>  	}
>  	if (strlen(card->components) + 1 + len + 1 > sizeof(card->components)) {
> +		snd_printk(KERN_ERR "components = %s + %s\n",
> +				card->components, component);
>  		snd_BUG();
>  		return -ENOMEM;
>  	}
> 
> 
> [   12.590150] ALSA sound/core/init.c:710: components = HDA:11d4194a,103c3037,00100400 HDA:11c11040,103c1378,00100200 + HDA:80862802,80860101,00100000
> [   12.590163] ------------[ cut here ]------------
> [   12.590166] WARNING: at sound/core/init.c:711 snd_component_add+0xfa/0x110 [snd]()
> [   12.590168] BUG?
> [   12.590170] Modules linked in: snd_hda_intel(+) snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss iwlagn snd_pcm snd_timer iwlcore snd_page_alloc snd_hwdep rfkill snd pcspkr led_class sky2 wmi soundcore uhci_hcd ohci_hcd ehci_hcd
> [   12.590197] Pid: 2410, comm: modprobe Not tainted 2.6.27-rc7 #4
(snip)

Argh, that's bad. 
Then I agree with increasing the components as a simple workaround.

How about the patch below?  The control protocol number is increased
for this change as well.


thanks,

Takashi

diff --git a/include/sound/asound.h b/include/sound/asound.h
index 3eaf155..fbfe992 100644
--- a/include/sound/asound.h
+++ b/include/sound/asound.h
@@ -696,7 +696,7 @@ struct snd_timer_tread {
  *                                                                          *
  ****************************************************************************/
 
-#define SNDRV_CTL_VERSION		SNDRV_PROTOCOL_VERSION(2, 0, 5)
+#define SNDRV_CTL_VERSION		SNDRV_PROTOCOL_VERSION(2, 0, 6)
 
 struct snd_ctl_card_info {
 	int card;			/* card number */
@@ -707,8 +707,7 @@ struct snd_ctl_card_info {
 	unsigned char longname[80];	/* name + info text about soundcard */
 	unsigned char reserved_[16];	/* reserved for future (was ID of mixer) */
 	unsigned char mixername[80];	/* visual mixer identification */
-	unsigned char components[80];	/* card components / fine identification, delimited with one space (AC97 etc..) */
-	unsigned char reserved[48];	/* reserved for future */
+	unsigned char components[128];	/* card components / fine identification, delimited with one space (AC97 etc..) */
 };
 
 typedef int __bitwise snd_ctl_elem_type_t;
diff --git a/include/sound/core.h b/include/sound/core.h
index 558b962..221554e 100644
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -114,7 +114,7 @@ struct snd_card {
 	char shortname[32];		/* short name of this soundcard */
 	char longname[80];		/* name of this soundcard */
 	char mixername[80];		/* mixer name */
-	char components[80];		/* card components delimited with
+	char components[128];		/* card components delimited with
 								space */
 	struct module *module;		/* top-level module */