Messages in this thread | | | Subject | [BUG] unsafe reset in ac97_codec.c | From | Liam Girdwood <> | Date | Tue, 03 Feb 2004 15:42:28 +0000 |
| |
Hi
Does anyone know why ac97_codec.c does a register reset of the codec during device probing. i.e.
/* probing AC97 codec, AC97 2.0 says that bit 15 of register 0x00 (reset) should * be read zero. * * FIXME: is the following comment outdated? -jgarzik * Probing of AC97 in this way is not reliable, it is not even SAFE !! */ codec->codec_write(codec, AC97_RESET, 0L);
IMO, this is unsafe because it can also reset the codec into it's default power state which can be "power down". This is not normally a problem for PC's, but some battery powered devices have the default codec state as "power down" to conserve power.
Was this introduced as a workaround for some buggy device ? If no one objects I'll submit a patch.
Liam
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |