linux-kernel - Re: [PATCH v2 2/4] ASoC: qcom: common: add Display port Jack function

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Message-ID: <Zlj_4IuZqnC3gESL@eriador.lumag.spb.ru>
Date: Fri, 31 May 2024 01:38:24 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc: Johan Hovold <johan@...nel.org>, broonie@...nel.org, perex@...ex.cz,
	tiwai@...e.com, lgirdwood@...il.com, alsa-devel@...a-project.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/4] ASoC: qcom: common: add Display port Jack function

On Thu, May 09, 2024 at 09:59:40AM +0100, Srinivas Kandagatla wrote:
> 
> 
> On 29/04/2024 15:54, Johan Hovold wrote:
> > On Tue, Apr 23, 2024 at 04:55:32PM +0100, Srinivas Kandagatla wrote:
> > > On 23/04/2024 13:02, Johan Hovold wrote:
> > > > On Mon, Apr 22, 2024 at 02:43:52PM +0100, Srinivas Kandagatla wrote:
> > > > >    static const struct snd_soc_dapm_widget qcom_jack_snd_widgets[] = {
> > > > >    	SND_SOC_DAPM_HP("Headphone Jack", NULL),
> > > > >    	SND_SOC_DAPM_MIC("Mic Jack", NULL),
> > > > > +	SND_SOC_DAPM_SPK("HDMI/DP0 Jack", NULL),
> > > > > +	SND_SOC_DAPM_SPK("HDMI/DP1 Jack", NULL),
> > > > > +	SND_SOC_DAPM_SPK("HDMI/DP2 Jack", NULL),
> > > > 
> > > > Shouldn't these be split in dedicated HDMI and DP jacks too? What if you
> > > > have a machine with HDMI and DP jacks which would otherwise both claim
> > > > "HDMI/DP0"?
> > > 
> > > These map to the Jack's added as part of qcom_snd_dp_jack_setup and
> > > belong to DISPLAY_PORT_RX_0, DISPLAY_PORT_RX_1, DISPLAY_PORT_RX_2.
> > > 
> > > If its going via USB-C DP controller it will be either DP or an HDMI ?
> > 
> > It will always be DP out of the machine even if an adapter can convert
> > to HDMI internally.
> > 
> > The DRM ports are called "DP-1" and "DP-2" so it seems we should match
> > that.
> > 
> > > This is the most common naming for the USB-C DP/HDMI jack events.
> > 
> > It looks like some Intel machines use names like "HDMI/DP, pcm=%d Jack"
> > (with a pcm device number), but we also have "DP Jack". Not sure which
> > are are used with USB-C, though. (Or if the former actually support HDMI
> > altmode.)
> 
> I checked this on my machine which has usb-c and I can confirm using HDMI/DP
> naming for these jack.
> 
> Either way I don't mind having any names, but my point here is to be more
> consistent across.

I fear it is till not consistent. On the Intel laptop I see following
jacks:

numid=18,iface=CARD,name='HDMI/DP,pcm=3 Jack'
numid=24,iface=CARD,name='HDMI/DP,pcm=7 Jack'
numid=30,iface=CARD,name='HDMI/DP,pcm=8 Jack'

On the other hand Mediatek and RockChip use just 'DP Jack'.

I'd suggest settling on the latter option. We are closer to MTK and
RockChip rather than Intel.

BTW: a platform can easily have 4 (x1e8100) or even 8 (sc8280xp) DP
outputs. Could you please point out why there are just 3 jacks?

> --srini
> > 
> > > Qualcomm LPASS in some older SoCs had a dedicated HDMI interface which
> > > is different to this one.
> > > 
> > > Usual Other ways to connect HDMI is via external HDMI Bridge using I2S
> > > interface which totally different to this DP interface.
> > 
> > Sure, but if there's ever a design with such a port then it will be
> > called "HDMI Jack" and then the "HDMI in "HDMI/DP0 Jack" is unnecessary
> > and confusing when it is always DP out.
> > 
> > Johan

-- 
With best wishes
Dmitry