Hi,
so far, we use snd_card_new() function to create a card instance.
A known problem regarding this API is that it doesn't return a proper
error code, thus the probe callback always returns -ENOMEM (or
whatever the driver defines) no matter which error occurred actually.
A typical case is the card slot conflict. Even in such a case, it
returns -ENOMEM, which may mislead the user.
For fixing this situation, I'd like to convert from snd_card_new() to
a new function, snd_card_create():
int snd_card_create(int idx, const char *id,
struct module *module, int extra_size,
struct snd_card **card_ret);
and provides snd_card_new() as a wrapper with deprecated flag:
static inline __deprecated
struct snd_card *snd_card_new(int idx, const char *id,
struct module *module, int extra_size)
{
struct snd_card *card;
if (snd_card_create(idx, id, module, extra_size, &card) < 0)
return NULL;
return card;
}
The merit of creating a new function is that the older and out-of-tree
codes (like xfi) work without modification. There is alternative
option, namely to use PTR_ERR() and keep the function as is.
But this has no advantage in practice -- it can't detect the old API
at build time, and it may Oops.
The preliminary patches are found in test/snd_card_new-err branch
of sound git tree:
git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6.git test/snd_card_new-err
If anyone finds problems with this, please let me know.
thanks,
Takashi
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