At Mon, 17 Jan 2011 23:20:03 -0800, Brian Bloniarz wrote:
On my M-Audio Delta 66 (rev. E), I see this line: [ 23.248721] invalid CS8427 signature 0x0: let me try again...
This is caused by the first request to the CS8427 failing, and this workaround:
commit 4eb4550ab37d351ab0973ccec921a5a2d8560ec7, Author: Takashi Iwai tiwai@suse.de Date: Thu Sep 20 17:34:57 2007 +0200
[ALSA] Workaround for invalid signature read of CS8427 Reading the signature of CS8427 over SPI/I2C fails on some devices by mysterious reason. In most cases, however, it succeeds at the sequential read. So, let's give a second chance to check the signature again. Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Jaroslav Kysela <perex@suse.cz>I have a theory, please read the patch and patch description below. With the patch applied, the printk goes away.
Does this sound like a reasonable theory? Does anyone recall, did this failed read occur on any cards besides M-Audio Delta? I'm wondering if this is the whole explanation, in which case the previous workaround could be removed.
[PATCH] [ALSA] ice1712 delta - initialize SPI clock.
The driver was using an initial value for the clock on the SPI bus which was read from ICE1712 EEPROM, ice->eeprom.data[ICE_EEP1_GPIO_STATE] & ICE1712_DELTA_AP_CCLK (0x02)
It appears some cards have it default high, some cards have it default low. On my Delta 66 rev. E: $ cat /proc/asound/M66/ice1712 | grep 'GPIO state' GPIO state : 0x70 /* ICE1712_DELTA_AP_CCLK bit is zero */ On my Audiophile 2496: $ cat /proc/asound/M2496/ice1712 | grep 'GPIO state' GPIO state : 0xfe /* ICE1712_DELTA_AP_CCLK bit is one */
It must be raised before the first SPI write happens, or the write will fail, leading to:
[ 23.248721] invalid CS8427 signature 0x0: let me try again...
I theorize that 4eb4550ab37d351ab0973ccec921a5a2d8560ec7 is no longer needed, it was a different way to workaround the problem.
Yes, your fix looks sane (and safe). I'll queue it up later for 2.6.38 merge.
The retry-code can be kept for a while as it's basically harmless for the succeeded case. We can remove it eventually later, but I doubt we can be 100% sure about such a thing ;)
thanks,
Takashi
Signed-off-by: Brian Bloniarz brian.bloniarz@gmail.com
sound/pci/ice1712/delta.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/sound/pci/ice1712/delta.c b/sound/pci/ice1712/delta.c index 7b62de0..84a6031 100644 --- a/sound/pci/ice1712/delta.c +++ b/sound/pci/ice1712/delta.c @@ -622,6 +622,13 @@ static int __devinit snd_ice1712_delta_init(struct snd_ice1712 *ice) break; }
/* initialize the SPI clock to high */unsigned char tmp;tmp = snd_ice1712_read(ice, ICE1712_IREG_GPIO_DATA);tmp |= ICE1712_DELTA_AP_CCLK;snd_ice1712_write(ice, ICE1712_IREG_GPIO_DATA, tmp);udelay(5);/* initialize spdif */ switch (ice->eeprom.subvendor) { case ICE1712_SUBDEVICE_AUDIOPHILE:-- 1.7.1