[alsa-devel] [PATCH] ASoC: cs42l73: Don't mix SNDRV_PCM_RATE_KNOT with specific rates
SNDRV_PCM_RATE_KNOT means that the device can support rates that can not be expressed using the rate bits. The driver will provide a list of those rates specified through constraints. Any rate bits that are set in the rates mask will be ignored. So setting other rate bits besides SNDRV_PCM_RATE_KNOT wont have any effect, but might be confusing to the casual reader, so remove them.
Signed-off-by: Lars-Peter Clausen lars@metafoo.de --- sound/soc/codecs/cs42l73.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/sound/soc/codecs/cs42l73.c b/sound/soc/codecs/cs42l73.c index 549d5d6..7cae046 100644 --- a/sound/soc/codecs/cs42l73.c +++ b/sound/soc/codecs/cs42l73.c @@ -1255,9 +1255,6 @@ static int cs42l73_pcm_startup(struct snd_pcm_substream *substream, return 0; }
-/* SNDRV_PCM_RATE_KNOT -> 12000, 24000 Hz, limit with constraint list */ -#define CS42L73_RATES (SNDRV_PCM_RATE_8000_48000 | SNDRV_PCM_RATE_KNOT) -
#define CS42L73_FORMATS (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S20_3LE |\ SNDRV_PCM_FMTBIT_S24_LE) @@ -1278,14 +1275,14 @@ static struct snd_soc_dai_driver cs42l73_dai[] = { .stream_name = "XSP Playback", .channels_min = 1, .channels_max = 2, - .rates = CS42L73_RATES, + .rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .capture = { .stream_name = "XSP Capture", .channels_min = 1, .channels_max = 2, - .rates = CS42L73_RATES, + .rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .ops = &cs42l73_ops, @@ -1298,14 +1295,14 @@ static struct snd_soc_dai_driver cs42l73_dai[] = { .stream_name = "ASP Playback", .channels_min = 2, .channels_max = 2, - .rates = CS42L73_RATES, + .rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .capture = { .stream_name = "ASP Capture", .channels_min = 2, .channels_max = 2, - .rates = CS42L73_RATES, + .rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .ops = &cs42l73_ops, @@ -1318,14 +1315,14 @@ static struct snd_soc_dai_driver cs42l73_dai[] = { .stream_name = "VSP Playback", .channels_min = 1, .channels_max = 2, - .rates = CS42L73_RATES, + .rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .capture = { .stream_name = "VSP Capture", .channels_min = 1, .channels_max = 2, - .rates = CS42L73_RATES, + .rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .ops = &cs42l73_ops,
On Feb 4, 2014, at 13:55, "Lars-Peter Clausen" lars@metafoo.de wrote:
SNDRV_PCM_RATE_KNOT means that the device can support rates that can not be expressed using the rate bits. The driver will provide a list of those rates specified through constraints. Any rate bits that are set in the rates mask will be ignored. So setting other rate bits besides SNDRV_PCM_RATE_KNOT wont have any effect, but might be confusing to the casual reader, so remove them.
Signed-off-by: Lars-Peter Clausen lars@metafoo.de
sound/soc/codecs/cs42l73.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/sound/soc/codecs/cs42l73.c b/sound/soc/codecs/cs42l73.c index 549d5d6..7cae046 100644 --- a/sound/soc/codecs/cs42l73.c +++ b/sound/soc/codecs/cs42l73.c @@ -1255,9 +1255,6 @@ static int cs42l73_pcm_startup(struct snd_pcm_substream *substream, return 0; }
-/* SNDRV_PCM_RATE_KNOT -> 12000, 24000 Hz, limit with constraint list */ -#define CS42L73_RATES (SNDRV_PCM_RATE_8000_48000 | SNDRV_PCM_RATE_KNOT)
#define CS42L73_FORMATS (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S20_3LE |\ SNDRV_PCM_FMTBIT_S24_LE) @@ -1278,14 +1275,14 @@ static struct snd_soc_dai_driver cs42l73_dai[] = { .stream_name = "XSP Playback", .channels_min = 1, .channels_max = 2,
.rates = CS42L73_RATES,
.rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .capture = { .stream_name = "XSP Capture", .channels_min = 1, .channels_max = 2,
.rates = CS42L73_RATES,
.rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .ops = &cs42l73_ops,@@ -1298,14 +1295,14 @@ static struct snd_soc_dai_driver cs42l73_dai[] = { .stream_name = "ASP Playback", .channels_min = 2, .channels_max = 2,
.rates = CS42L73_RATES,
.rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .capture = { .stream_name = "ASP Capture", .channels_min = 2, .channels_max = 2,
.rates = CS42L73_RATES,
.rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .ops = &cs42l73_ops,@@ -1318,14 +1315,14 @@ static struct snd_soc_dai_driver cs42l73_dai[] = { .stream_name = "VSP Playback", .channels_min = 1, .channels_max = 2,
.rates = CS42L73_RATES,
.rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .capture = { .stream_name = "VSP Capture", .channels_min = 1, .channels_max = 2,
.rates = CS42L73_RATES,
.rates = SNDRV_PCM_RATE_KNOT, .formats = CS42L73_FORMATS, }, .ops = &cs42l73_ops,-- 1.8.0
I don't see how this makes it any less confusing to the casual reader. I think the define works well in the descriptive sense. maybe a comment about what KNOT really means instead of just using a non-rate define?
Thanks, Brian
On 02/04/2014 09:30 PM, Austin, Brian wrote:
On Feb 4, 2014, at 13:55, "Lars-Peter Clausen" lars@metafoo.de wrote:
SNDRV_PCM_RATE_KNOT means that the device can support rates that can not be expressed using the rate bits. The driver will provide a list of those rates specified through constraints. Any rate bits that are set in the rates mask will be ignored. So setting other rate bits besides SNDRV_PCM_RATE_KNOT wont have any effect, but might be confusing to the casual reader, so remove them.
Signed-off-by: Lars-Peter Clausen lars@metafoo.de
I don't see how this makes it any less confusing to the casual reader. I think the define works well in the descriptive sense. maybe a comment about what
KNOT really
means instead of just using a non-rate define?
The thing is SNDRV_PCM_RATE_8000_48000 does something if SNDRV_PCM_RATE_{KNOT,CONTINUOUS} is not set, but does nothing at all if either of them is set. While when reading the code it will, in my opinion, give the impression that the rates that are specified by SNDRV_PCM_RATE_8000_48000 are definitely among the supported rates and somewhere else additional rates are specified as well. But this is not the case all the supported rates need to be specified somewhere else, e.g. by a rate list constraint. I find this confusing when casually reading the code. And this is the only driver that does it.
Also there was a bug, which is now fixed, where additionally specifying rates in the rate bitmap when KNOT or CONTINUOUS was set did something, but did the wrong thing and caused additional rates which where outside of the range of the rates set in the bitmap to be ignored. Better avoid that by not mixing KNOT or CONTINUOUS with other rate bits.
- Lars
On 05/02/14 10:01, Lars-Peter Clausen wrote:
e.g. by a rate list constraint. I find this confusing when casually reading the code.
And this is the only driver that does it.
A quick grep through the sound tree for "KNOT" shows that there are many drivers that do?
Just a example:
pci/intel8x0m.c: .rates = SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_16000 | SNDRV_PCM_RATE_KNOT
Do these need 'fixing'?
At Wed, 05 Feb 2014 10:49:06 +1300, Eliot Blennerhassett wrote:
On 05/02/14 10:01, Lars-Peter Clausen wrote:
e.g. by a rate list constraint. I find this confusing when casually reading the code.
And this is the only driver that does it.
A quick grep through the sound tree for "KNOT" shows that there are many drivers that do?
Just a example:
pci/intel8x0m.c: .rates = SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_16000 | SNDRV_PCM_RATE_KNOT
Do these need 'fixing'?
It would be no "fix" but rather a "cleanup".
Takashi
At Wed, 05 Feb 2014 10:49:06 +1300, Eliot Blennerhassett wrote:
On 05/02/14 10:01, Lars-Peter Clausen wrote:
e.g. by a rate list constraint. I find this confusing when casually reading the code.
And this is the only driver that does it.
A quick grep through the sound tree for "KNOT" shows that there are many drivers that do?
Just a example:
pci/intel8x0m.c: .rates = SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_16000 | SNDRV_PCM_RATE_KNOT
Do these need 'fixing'?
It would be no "fix" but rather a "cleanup".
Takashi
On Feb 4, 2014, at 3:01 PM, Lars-Peter Clausen lars@metafoo.de wrote:
On 02/04/2014 09:30 PM, Austin, Brian wrote:
On Feb 4, 2014, at 13:55, "Lars-Peter Clausen" lars@metafoo.de wrote:
SNDRV_PCM_RATE_KNOT means that the device can support rates that can not be expressed using the rate bits. The driver will provide a list of those rates specified through constraints. Any rate bits that are set in the rates mask will be ignored. So setting other rate bits besides SNDRV_PCM_RATE_KNOT wont have any effect, but might be confusing to the casual reader, so remove them.
Signed-off-by: Lars-Peter Clausen lars@metafoo.de
I don't see how this makes it any less confusing to the casual reader. I think the define works well in the descriptive sense. maybe a comment about what KNOT really means instead of just using a non-rate define?
The thing is SNDRV_PCM_RATE_8000_48000 does something if SNDRV_PCM_RATE_{KNOT,CONTINUOUS} is not set, but does nothing at all if either of them is set.
While when reading the code it will, in my opinion, give the impression that the rates that are specified by SNDRV_PCM_RATE_8000_48000 are definitely among the supported rates and somewhere else additional rates are specified as well. But this is not the case all the supported rates need to be specified somewhere else, e.g. by a rate list constraint. I find this confusing when casually reading the code. And this is the only driver that does it.
But that is the case is it not? The device supports the rates within 8000 and 48000. There are additional rates that need to be specified. If anything I see the issue with having to specify ALL the rates supported in the constraint list. The KNOT is an addition to the .rates member. The KNOT list is added to the .rates member in the dai driver.
Also there was a bug, which is now fixed, where additionally specifying rates in the rate bitmap when KNOT or CONTINUOUS was set did something, but did the wrong thing and caused additional rates which where outside of the range of the rates set in the bitmap to be ignored. Better avoid that by not mixing KNOT or CONTINUOUS with other rate bits.
Shouldn’t the rates outside of the range of the rates bitmap be ignored? Maybe this is a wrong interpretation of how this is supposed to work, but I thought you specify the rates that are available and add a constraint list to add rates that are not defined in ALSA. Not that the KNOT value would mean that you also have rates outside of the values you specified.
example: SNDRV_PCM_RATE_8000_48000 | | SNDRV_PCM_RATE_KNOT means that I support all rates defined between 8 and 48 PLUS addition rates INSIDE of 8 and 48. Is this correct?
Sorry Lars, I just want to have a clear understanding of what the bug is and how this fixes it.
Thanks, Brian
On 02/05/2014 03:35 PM, Austin, Brian wrote:
On Feb 4, 2014, at 3:01 PM, Lars-Peter Clausen lars@metafoo.de wrote:
On 02/04/2014 09:30 PM, Austin, Brian wrote:
On Feb 4, 2014, at 13:55, "Lars-Peter Clausen" lars@metafoo.de wrote:
SNDRV_PCM_RATE_KNOT means that the device can support rates that can not be expressed using the rate bits. The driver will provide a list of those rates specified through constraints. Any rate bits that are set in the rates mask will be ignored. So setting other rate bits besides SNDRV_PCM_RATE_KNOT wont have any effect, but might be confusing to the casual reader, so remove them.
Signed-off-by: Lars-Peter Clausen lars@metafoo.de
I don't see how this makes it any less confusing to the casual reader. I think the define works well in the descriptive sense. maybe a comment about what KNOT really means instead of just using a non-rate define?
The thing is SNDRV_PCM_RATE_8000_48000 does something if SNDRV_PCM_RATE_{KNOT,CONTINUOUS} is not set, but does nothing at all if either of them is set.
While when reading the code it will, in my opinion, give the impression that the rates that are specified by SNDRV_PCM_RATE_8000_48000 are definitely among the supported rates and somewhere else additional rates are specified as well. But this is not the case all the supported rates need to be specified somewhere else, e.g. by a rate list constraint. I find this confusing when casually reading the code. And this is the only driver that does it.
But that is the case is it not? The device supports the rates within 8000 and 48000. There are additional rates that need to be specified. If anything I see the issue with having to specify ALL the rates supported in the constraint list. The KNOT is an addition to the .rates member. The KNOT list is added to the .rates member in the dai driver.
Yep, but that's not how it works and why I think it is confusing to keep things the SNDRV_PCM_RATE_8000_48000 in there, as it might cause people to think that this is how it works.
When a substream is opened the constraints are set to be as permissive as possible. E.g. for rates this means any rate is considered valid. Going from there the constraints code allows you to further restrict things. This is done by attaching rules to the constraint. The result is the intersection of all the rules attached to the constraint. E.g. if you have one rule that says the rate must be between 16000 and 64000 and another rule that says the rate must be one of 8000, 16000, 32000 or 48000, the list of valid rates is 16000, 32000, 48000. Similar if you have one rule that says the rate must be one of 8000, 16000 or 32000 and another rule that says that the rate must be one of 16000, 22500 or 24000, the list of valid rates is 16000. It is only possible to further restrict the set of supported rates by one rule, it is not possible to make it more permissive.
When you set the rates field (and omit the KNOT or CONTINUOUS flags) the ALSA core will install one rule that will limit the supported rates to those set in the rates field. When you use snd_pcm_hw_constraint_list() this will add a second rule that will only allow rates in the array you specified for that constraint. So the result will be that only those rates that are allowed by both rules.
That's why you need to specify all supported rates in the constraint. Note that ALSA core will do nothing with the rates field if the KNOT or CONTINUOUS flag is set. Otherwise you wouldn't be able to specify rates outside of what can be specified using the standard rates.
Also there was a bug, which is now fixed, where additionally specifying rates in the rate bitmap when KNOT or CONTINUOUS was set did something, but did the wrong thing and caused additional rates which where outside of the range of the rates set in the bitmap to be ignored. Better avoid that by not mixing KNOT or CONTINUOUS with other rate bits.
Shouldn’t the rates outside of the range of the rates bitmap be ignored? Maybe this is a wrong interpretation of how this is supposed to work, but I thought you specify the rates that are available and add a constraint list to add rates that are not defined in ALSA. Not that the KNOT value would mean that you also have rates outside of the values you specified.
If you ignore rates outside the range of what is specified in the rates field you wouldn't be able to use rates that are lower or higher than what is possible to specify with the default rates.
example: SNDRV_PCM_RATE_8000_48000 | | SNDRV_PCM_RATE_KNOT means that I support all rates defined between 8 and 48 PLUS addition rates INSIDE of 8 and 48. Is this correct?
It means you support some rates that need to be further specified somewhere else. If SNDRV_PCM_RATE_KNOT (or SNDRV_PCM_RATE_CONTINUOUS) is set in the rates field all other bits that might be set are fully ignored (And that's not a bug, it's a feature).
Sorry Lars, I just want to have a clear understanding of what the bug is and how this fixes it.
Thanks, Brian
There is no bug (anymore). I already fixed things up in the ALSA and ASoC core so that if KNOT or CONTINUOUS is set all the other bits are masked out from the rates field. Before that was done there was a bug that for some drivers rates were ignored that should have been valid. This patch is a cleanup that removes a code fragment that on the first look suggests that it does something while it actually does nothing. And I think you proved my point that this can be confusing and misleading :)
- Lars
On 2/5/14, 9:23 AM, "Lars-Peter Clausen" lars@metafoo.de wrote:
On 02/05/2014 03:35 PM, Austin, Brian wrote:
On Feb 4, 2014, at 3:01 PM, Lars-Peter Clausen lars@metafoo.de wrote:
On 02/04/2014 09:30 PM, Austin, Brian wrote:
On Feb 4, 2014, at 13:55, "Lars-Peter Clausen" lars@metafoo.de wrote:
SNDRV_PCM_RATE_KNOT means that the device can support rates that can not be expressed using the rate bits. The driver will provide a list of those rates specified through constraints. Any rate bits that are set in the rates mask will be ignored. So setting other rate bits besides SNDRV_PCM_RATE_KNOT wont have any effect, but might be confusing to the casual reader, so remove them.
Signed-off-by: Lars-Peter Clausen lars@metafoo.de
I don't see how this makes it any less confusing to the casual reader. I think the define works well in the descriptive sense. maybe a comment about what KNOT really means instead of just using a non-rate define?
The thing is SNDRV_PCM_RATE_8000_48000 does something if SNDRV_PCM_RATE_{KNOT,CONTINUOUS} is not set, but does nothing at all if either of them is set.
While when reading the code it will, in my opinion, give the impression that the rates that are specified by SNDRV_PCM_RATE_8000_48000 are definitely among the supported rates and somewhere else additional rates are specified as well. But this is not the case all the supported rates need to be specified somewhere else, e.g. by a rate list constraint. I find this confusing when casually reading the code. And this is the only driver that does it.
But that is the case is it not? The device supports the rates within 8000 and 48000. There are additional rates that need to be specified. If anything I see the issue with having to specify ALL the rates supported in the constraint list. The KNOT is an addition to the .rates member. The KNOT list is added to the .rates member in the dai driver.
Yep, but that's not how it works and why I think it is confusing to keep things the SNDRV_PCM_RATE_8000_48000 in there, as it might cause people to think that this is how it works.
When a substream is opened the constraints are set to be as permissive as possible. E.g. for rates this means any rate is considered valid. Going from there the constraints code allows you to further restrict things. This is done by attaching rules to the constraint. The result is the intersection of all the rules attached to the constraint. E.g. if you have one rule that says the rate must be between 16000 and 64000 and another rule that says the rate must be one of 8000, 16000, 32000 or 48000, the list of valid rates is 16000, 32000, 48000. Similar if you have one rule that says the rate must be one of 8000, 16000 or 32000 and another rule that says that the rate must be one of 16000, 22500 or 24000, the list of valid rates is 16000. It is only possible to further restrict the set of supported rates by one rule, it is not possible to make it more permissive.
When you set the rates field (and omit the KNOT or CONTINUOUS flags) the ALSA core will install one rule that will limit the supported rates to those set in the rates field. When you use snd_pcm_hw_constraint_list() this will add a second rule that will only allow rates in the array you specified for that constraint. So the result will be that only those rates that are allowed by both rules.
That's why you need to specify all supported rates in the constraint. Note that ALSA core will do nothing with the rates field if the KNOT or CONTINUOUS flag is set. Otherwise you wouldn't be able to specify rates outside of what can be specified using the standard rates.
Also there was a bug, which is now fixed, where additionally specifying rates in the rate bitmap when KNOT or CONTINUOUS was set did something, but did the wrong thing and caused additional rates which where outside of the range of the rates set in the bitmap to be ignored. Better avoid that by not mixing KNOT or CONTINUOUS with other rate bits.
Shouldn¹t the rates outside of the range of the rates bitmap be ignored? Maybe this is a wrong interpretation of how this is supposed to work, but I thought you specify the rates that are available and add a constraint list to add rates that are not defined in ALSA. Not that the KNOT value would mean that you also have rates outside of the values you specified.
If you ignore rates outside the range of what is specified in the rates field you wouldn't be able to use rates that are lower or higher than what is possible to specify with the default rates.
example: SNDRV_PCM_RATE_8000_48000 | | SNDRV_PCM_RATE_KNOT means that I support all rates defined between 8 and 48 PLUS addition rates INSIDE of 8 and 48. Is this correct?
It means you support some rates that need to be further specified somewhere else. If SNDRV_PCM_RATE_KNOT (or SNDRV_PCM_RATE_CONTINUOUS) is set in the rates field all other bits that might be set are fully ignored (And that's not a bug, it's a feature).
Sorry Lars, I just want to have a clear understanding of what the bug is and how this fixes it.
Thanks, Brian
There is no bug (anymore). I already fixed things up in the ALSA and ASoC core so that if KNOT or CONTINUOUS is set all the other bits are masked out from the rates field. Before that was done there was a bug that for some drivers rates were ignored that should have been valid. This patch is a cleanup that removes a code fragment that on the first look suggests that it does something while it actually does nothing. And I think you proved my point that this can be confusing and misleading :)
- Lars
Thanks for the explanation. I had a reverse understanding of what this actually does for the dai driver .rates coupled with the constraint list.
Thanks, Brian
On 2/4/14, 1:55 PM, "Lars-Peter Clausen" lars@metafoo.de wrote:
SNDRV_PCM_RATE_KNOT means that the device can support rates that can not be expressed using the rate bits. The driver will provide a list of those rates specified through constraints. Any rate bits that are set in the rates mask will be ignored. So setting other rate bits besides SNDRV_PCM_RATE_KNOT wont have any effect, but might be confusing to the casual reader, so remove them.
Signed-off-by: Lars-Peter Clausen lars@metafoo.de
Acked-by: Brian Austin brian.austin@cirrus.com
On Tue, Feb 04, 2014 at 08:55:31PM +0100, Lars-Peter Clausen wrote:
SNDRV_PCM_RATE_KNOT means that the device can support rates that can not be expressed using the rate bits. The driver will provide a list of those rates specified through constraints. Any rate bits that are set in the rates mask will be ignored. So setting other rate bits besides SNDRV_PCM_RATE_KNOT wont have any effect, but might be confusing to the casual reader, so remove them.
Applied, thanks.
participants (5)
-
Austin, Brian -
Eliot Blennerhassett -
Lars-Peter Clausen -
Mark Brown -
Takashi Iwai