Alsa-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Jyri Sarha <jyri.sarha@iki.fi>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Fabio Estevam <fabio.estevam@freescale.com>,
	alsa-devel@alsa-project.org, Takashi Iwai <tiwai@suse.de>,
	dri-devel@lists.freedesktop.org, Mark Brown <broonie@kernel.org>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Yakir Yang <ykk@rock-chips.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [alsa-devel] [PATCH RFC v2 10/13] sound/core: add DRM ELD helper
Date: Fri, 08 May 2015 13:56:02 +0300
Message-ID: <ef04b1827963c2746c252f65bfa0d172@kapsi.fi> (raw)
In-Reply-To: <20150405172608.GA12732@n2100.arm.linux.org.uk>

On 2015-04-05 20:26, Russell King - ARM Linux wrote:
> On Sun, Apr 05, 2015 at 06:46:13PM +0200, Takashi Iwai wrote:
>> At Sun, 5 Apr 2015 17:20:34 +0100,
>> Russell King - ARM Linux wrote:
>> > Since (afaik) ALSA has a lack of support for dynamic reconfiguration
>> > according to the attached device changing, the best we can do without
>> > a huge amount of re-work of HDMI support across all adapters is to
>> > process the capabilities of the attached device at prepare time
>> > according to the current capabilities.
>> 
>> Yeah, reconfiguration is tricky.  BTW, how is the HDMI unplug handled
>> during playback?
> 
> We don't handle it right now - and we don't have any notification to
> the audio drivers that that has happened.  Even if we did have such a
> notification, I'm not sure what the audio driver could do with it at
> the moment.
> 
>> > Implementing dynamic reconfiguration in ALSA is not something I want to
>> > get involved with, and as we /already/ have HDMI support merged in the
>> > kernel, this is not a blocker for at least trying to get some semblence
>> > of sanity, rather than having every driver re-implementing stuff like
>> > this.
>> 
>> Well, I didn't mean about the dynamic reconfiguration.  I thought of
>> rather min/max pairs, but it was just a wrong assumption.  Scratch
>> it.
>> 
>> One another question: don't we need to deal with the sample bits in
>> sad[2]?
> 
> It should, but I'm very wary about doing that without seeing more
> examples of real SADs.

If the same constraint setting helpers are to be used also with
external HDMI encoders with i2s interface, there should be an option
to leave out the constraints for the sample bits. There is no direct
connection between the number of bits on I2S and HDMI link. The CPU
DAI may apply its own constraints on the available sample formats and
too strict constraints at the encoder end may lead to zero available
formats.

Best regrads,
Jyri

> Right now, all my examples only support
> one SAD with either 2 channel or 6 channel audio at the standard
> (basic) 32, 44.1 and 48kHz rates.
> 
> The HDMI / CEA specs are very loose in their wording about the
> short audio descriptors.  I've no idea whether a sink can provide
> (for example) descriptors such as:
> 
> 	LPCM, 6 channel 32, 44.1, 48kHz
> 	LPCM, 2 channel, 32, 44.1, 48, 96, 192kHz
> 
> or whether have to describe that as a single descriptor.  I only
> have two TVs to test with here.
> 
> What I'm concerned about is that when the ALSA parameter refining
> starts, we start with (eg) 2-8 channels, 32-192kHz.  Given that,
> if we invoke the channel restriction before the rate restriction,
> we would end up limiting to 2 channel at 32-192kHz.  If we apply
> the restrictions in the opposite order, we'd restrict to 6
> channel, 32-48kHz.  Neither are obviously correct in this
> circumstance, and I don't really see a way to solve it given my
> understanding of the way ALSA's parameter refinement works.
> 
> I suspect this is why most HDMI drivers are implemented such that
> they take the maximum capabilities over all SADs, which would end
> up restricting audio in the above case to: up to 6 channels, at
> 32, 44.1, 48, 96 and 192kHz, even though 6 channel @ 192kHz isn't
> hasn't been indicated as supported.
> 
> Most of this is speculation though, based off what is in the
> documentation.  As I say, I don't have enough real-world examples
> to get a feel for what manufacturers _actually_ do to give a hint
> as to how the documentation should be interpreted.
> 
> So, maybe I should just copy what everyone else does and take the
> maximum of all descriptors...

  parent reply index

Thread overview: 74+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-02  9:20 [RFC v2 0/13] dw_hdmi cleanups, audio preparation, helpers and ahb audio support Russell King - ARM Linux
2015-04-02  9:21 ` [PATCH RFC v2 01/13] drm: imx/dw_hdmi: move phy comments Russell King
2015-04-02  9:21 ` [PATCH RFC v2 02/13] drm: bridge/dw_hdmi: clean up phy configuration Russell King
2015-04-02  9:21 ` [PATCH RFC v2 03/13] drm: bridge/dw_hdmi: clean up hdmi_set_clk_regenerator() Russell King
2015-04-02  9:21 ` [PATCH RFC v2 04/13] drm: bridge/dw_hdmi: use drm_hdmi_avi_infoframe_from_display_mode() Russell King
2015-04-02  9:21 ` [PATCH RFC v2 05/13] drm: bridge/dw_hdmi: simplify hdmi_config_AVI() a little Russell King
2015-04-02  9:21 ` [PATCH RFC v2 06/13] drm: bridge/dw_hdmi: remove mhsyncpolarity/mvsyncpolarity/minterlaced Russell King
2015-04-02  9:21 ` [PATCH RFC v2 07/13] drm: bridge/dw_hdmi: introduce interface to setting sample rate Russell King
2015-04-02  9:21 ` [PATCH RFC v2 08/13] drm: bridge/dw_hdmi: introduce interfaces to enable and disable audio Russell King
2015-04-02  9:22 ` [PATCH RFC v2 09/13] drm/edid: add function to help find SADs Russell King
2015-04-02  9:22 ` [PATCH RFC v2 10/13] sound/core: add DRM ELD helper Russell King
2015-04-05 15:57   ` Takashi Iwai
2015-04-05 16:20     ` Russell King - ARM Linux
2015-04-05 16:46       ` Takashi Iwai
2015-04-05 17:26         ` Russell King - ARM Linux
2015-05-06 17:02           ` Anssi Hannula
2015-05-07 10:41             ` Russell King - ARM Linux
2015-05-07 11:11               ` Lars-Peter Clausen
2015-05-08 10:56           ` Jyri Sarha [this message]
2015-05-08 11:42             ` [alsa-devel] " Russell King - ARM Linux
2015-05-05 22:35     ` Mark Brown
2015-05-06  8:58       ` Liam Girdwood
2015-05-08 13:16   ` [alsa-devel] " Jyri Sarha
2015-05-08 13:27     ` Russell King - ARM Linux
2015-05-08 13:37       ` Jyri Sarha
2015-04-02  9:22 ` [PATCH RFC v2 11/13] sound/core: add IEC958 channel status helper Russell King
2015-04-02  9:22 ` [PATCH RFC v2 12/13] drm: bridge/dw_hdmi-ahb-audio: add audio driver Russell King
2015-04-02  9:22 ` [PATCH RFC v2 13/13] drm: bridge/dw_hdmi-ahb-audio: parse ELD from HDMI driver Russell King
2015-05-09 10:25 ` [PATCH v3 0/13] dw_hdmi cleanups, audio preparation, helpers and ahb audio support Russell King - ARM Linux
2015-05-09 10:25   ` [PATCH 01/13] drm: imx/dw_hdmi: move phy comments Russell King
2015-05-09 10:26   ` [PATCH 02/13] drm: bridge/dw_hdmi: clean up phy configuration Russell King
2015-05-22 15:19     ` Yakir
2015-05-09 10:26   ` [PATCH 03/13] drm: bridge/dw_hdmi: clean up hdmi_set_clk_regenerator() Russell King
2015-05-22 15:22     ` Yakir
2015-05-09 10:26   ` [PATCH 04/13] drm: bridge/dw_hdmi: use drm_hdmi_avi_infoframe_from_display_mode() Russell King
2015-05-09 10:26   ` [PATCH 05/13] drm: bridge/dw_hdmi: simplify hdmi_config_AVI() a little Russell King
2015-05-09 10:26   ` [PATCH 06/13] drm: bridge/dw_hdmi: remove mhsyncpolarity/mvsyncpolarity/minterlaced Russell King
2015-05-09 10:26   ` [PATCH 07/13] drm: bridge/dw_hdmi: introduce interface to setting sample rate Russell King
2015-05-22 15:26     ` Yakir
2015-05-09 10:26   ` [PATCH 08/13] drm: bridge/dw_hdmi: introduce interfaces to enable and disable audio Russell King
2015-05-22 15:28     ` Yakir
2015-05-09 10:26   ` [PATCH 09/13] drm/edid: add function to help find SADs Russell King
2015-05-09 10:26   ` [PATCH 10/13] sound/core: add DRM ELD helper Russell King
2015-05-22 12:20     ` [alsa-devel] " Mark Brown
2015-05-22 13:15       ` Russell King - ARM Linux
2015-05-22 13:30         ` Takashi Iwai
2015-05-22 13:53           ` Russell King - ARM Linux
2015-05-22 13:54             ` Takashi Iwai
2015-05-22 14:00               ` Russell King - ARM Linux
2015-05-22 14:02                 ` Takashi Iwai
2015-05-22 14:05                   ` Takashi Iwai
2015-05-22 16:12                     ` Russell King - ARM Linux
2015-05-09 10:26   ` [PATCH 11/13] sound/core: add IEC958 channel status helper Russell King
2015-05-22 12:40     ` Mark Brown
2015-05-09 10:26   ` [PATCH 12/13] drm: bridge/dw_hdmi-ahb-audio: add audio driver Russell King
2015-05-09 16:49     ` [alsa-devel] " Anssi Hannula
2015-05-09 16:55       ` Russell King - ARM Linux
2015-05-09 17:07         ` Anssi Hannula
2015-05-09 17:40           ` Russell King - ARM Linux
2015-05-09 17:53             ` Russell King - ARM Linux
2015-05-09 17:55             ` Anssi Hannula
2015-05-09 18:11               ` Russell King - ARM Linux
2015-05-10 18:59                 ` Anssi Hannula
2015-05-10 19:33                   ` Russell King - ARM Linux
2015-05-10 20:47                     ` Anssi Hannula
2015-05-11 15:58                     ` Mark Brown
2015-05-09 10:26   ` [PATCH 13/13] drm: bridge/dw_hdmi-ahb-audio: parse ELD from HDMI driver Russell King
2015-05-27 10:43     ` Daniel Vetter
2015-05-27 11:43       ` Mark Brown
2015-05-27 17:31       ` Russell King - ARM Linux
2015-05-27 21:29         ` Daniel Vetter
2015-05-27 21:44           ` Russell King - ARM Linux
2015-05-28  6:43             ` Daniel Vetter
2015-05-28  4:56         ` [alsa-devel] " Takashi Iwai

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=ef04b1827963c2746c252f65bfa0d172@kapsi.fi \
    --to=jyri.sarha@iki.fi \
    --cc=alsa-devel@alsa-project.org \
    --cc=broonie@kernel.org \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=fabio.estevam@freescale.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux@arm.linux.org.uk \
    --cc=p.zabel@pengutronix.de \
    --cc=tiwai@suse.de \
    --cc=ykk@rock-chips.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

Alsa-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/alsa-devel/0 alsa-devel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 alsa-devel alsa-devel/ https://lore.kernel.org/alsa-devel \
		alsa-devel@alsa-project.org
	public-inbox-index alsa-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.alsa-project.alsa-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git