linux-amlogic.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
From: Jerome Brunet <jbrunet@baylibre.com>
To: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	Mark Brown <broonie@kernel.org>,
	Liam Girdwood <lgirdwood@gmail.com>
Cc: alsa-devel@alsa-project.org,
	Stephan Gerhold <stephan@gerhold.net>,
	Kevin Hilman <khilman@baylibre.com>,
	linux-kernel@vger.kernel.org, zhangn1985@outlook.com,
	linux-amlogic@lists.infradead.org
Subject: Re: [PATCH] ASoC: core: restore dpcm flags semantics
Date: Fri, 31 Jul 2020 10:06:03 +0200	[thread overview]
Message-ID: <1ja6zg85xw.fsf@starbuckisacylon.baylibre.com> (raw)
In-Reply-To: <936d6e37-0ad0-b0d7-814a-1ace12087746@linux.intel.com>


On Thu 30 Jul 2020 at 18:06, Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> wrote:

> On 7/30/20 4:04 AM, Jerome Brunet wrote:
>>
>> On Wed 29 Jul 2020 at 17:56, Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> wrote:
>>
>>> On 7/29/20 10:46 AM, Jerome Brunet wrote:
>>>> commit b73287f0b0745 ('ASoC: soc-pcm: dpcm: fix playback/capture checks')
>>>> changed dpcm_playback and dpcm_capture semantic by throwing an error if
>>>> these flags are not aligned with DAIs capabilities on the link.
>>>>
>>>> The former semantic did not force the flags and DAI caps to be aligned.
>>>> The flag previously allowed card drivers to disable a stream direction on
>>>> a link (whether or not such feature is deemed useful).
>>>>
>>>> With change ('ASoC: core: use less strict tests for dailink capabilities')
>>>> an error is thrown if the flags and and the DAI caps are not aligned. Those
>>>> parameters were not meant to aligned initially. No technical reason was
>>>> given about why cards should now be considered "broken" in such condition
>>>> is not met, or why it should be considered to be an improvement to enforce
>>>> that.
>>>>
>>>> Forcing the flags to be aligned with DAI caps just make the information
>>>> the flag carry redundant with DAI caps, breaking a few cards along the way.
>>>>
>>>> This change drops the added error conditions and restore the initial flag
>>>> semantics.
>>>
>>> or rather lack thereof.
>>
>> Again, why ? All there is so far is your personal preference. no facts.
>
> What would be the meaning/purpose of a dailink with .dpcm_capture set, with
> only dais that support playback only?
>
> What would be the meaning/purpose of a dailink with .capture_only set, but
> with a dai that supports playback?

You get to throw an error in those case

>
> What happens if none of these flags are set?

I think I already suggested to throw an error in the initial review of
your patch

>
> What happens when all these flags are set?

I don't see the problem here

>
> No one seems to know, so my suggestion is to align first on consistent
> configurations, then see what can be removed.
>
>>   * What we had gave capabilities to the link, independent of the DAI
>>     components. ASoC just computes the intersection of all that to
>>     determine which direction needs to be enabled. Seems rather simple
>>     and straight forward.
>
> that's what my last patch did, and when there is no intersection it
> complains. Please clarify what you expect when there is no overlap between
> dai and dailink capabilities. Keep in mind that we have a mix of hard-codec
> configuration and DT-created ones, your case is not the general one.
>
>>   * It worked for every user of DPCM so a far.
>
> Not completely true, when Morimoto-san added snd_soc_dai_stream_valid() it
> exposed tons of cases where the information on direction was not provided
> in a reliable at the DAI level. I will assert that we are still finding out
> cases with broken DAI configurations, and as a result we will also find
> broken dailink configurations. Your picture of DPCM as a perfectly
> functional system that I broke is a distortion of reality.

If it was not working, it was certainly not clear in the changelog.
What's clear is the regression it caused

>
> The reality is that we have to work in steps, first make sure all DAIs are
> properly described, then work on the dailinks and optimize at a later
> point. we will need warnings to find out what the problem cases are, and
> move slowly.

Sure, have it your way

_______________________________________________
linux-amlogic mailing list
linux-amlogic@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-amlogic

  parent reply	other threads:[~2020-07-31  8:06 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200723180533.220312-1-pierre-louis.bossart@linux.intel.com>
2020-07-29 15:46 ` [PATCH] ASoC: core: restore dpcm flags semantics Jerome Brunet
2020-07-29 15:56   ` Pierre-Louis Bossart
2020-07-30  9:04     ` Jerome Brunet
2020-07-30 16:06       ` Pierre-Louis Bossart
2020-07-30 18:52         ` Mark Brown
2020-07-31 12:16           ` Jerome Brunet
2020-07-31 17:42             ` Mark Brown
2020-07-31  8:06         ` Jerome Brunet [this message]
2020-07-30 18:12       ` Mark Brown

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1ja6zg85xw.fsf@starbuckisacylon.baylibre.com \
    --to=jbrunet@baylibre.com \
    --cc=alsa-devel@alsa-project.org \
    --cc=broonie@kernel.org \
    --cc=khilman@baylibre.com \
    --cc=lgirdwood@gmail.com \
    --cc=linux-amlogic@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pierre-louis.bossart@linux.intel.com \
    --cc=stephan@gerhold.net \
    --cc=zhangn1985@outlook.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).