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Sat, 8 Nov 2025 09:21:02 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id YXZ3EX4LD2krQAAAD6G6ig (envelope-from ); Sat, 08 Nov 2025 09:21:02 +0000 Date: Sat, 08 Nov 2025 10:21:01 +0100 Message-ID: <874ir4ribm.wl-tiwai@suse.de> From: Takashi Iwai To: Srinivas Kandagatla Cc: Mark Brown , Takashi Iwai , linux-sound , wtaymans@redhat.com, arun@asymptotic.io, Jaroslav Kysela , lkml , Krzysztof Kozlowski , Dmitry Baryshkov Subject: Re: DP/HDMI Jack and Pipewire In-Reply-To: <76b8ca1d-040b-472e-9804-5c0c0100b5b5@oss.qualcomm.com> References: <76b8ca1d-040b-472e-9804-5c0c0100b5b5@oss.qualcomm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/27.2 Mule/6.0 Precedence: bulk X-Mailing-List: linux-sound@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 911DF22ADA X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-3.51 / 50.00]; BAYES_HAM(-3.00)[99.99%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RCPT_COUNT_SEVEN(0.00)[10]; FUZZY_RATELIMITED(0.00)[rspamd.com]; TO_DN_SOME(0.00)[]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.de:mid,suse.de:dkim]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -3.51 X-Spam-Level: On Fri, 07 Nov 2025 11:15:50 +0100, Srinivas Kandagatla wrote: > > Hi Everyone, > > On Qualcomm platforms we have an issue enabling Display port on a full > Distro setup with pipewire and wireplumber in place. > > The issue is that Display port Audio IP on Qualcomm SoC is powered off > if there is no Display connected. It make sense to keep it in this low > power mode when there is no use. And the DP IP is not expecting any data > in this state and any attempt to configure or send data would result in > error from DSP. > > However, we create PCM devices and jacks for all audio sinks and > sources, including DisplayPort DAI links. When PipeWire starts up > without any awareness of jack state it probes all available PCM devices, > including the DisplayPort ones. Since no display is connected, the > prepare callback for DP fails, leading PipeWire to mark the sound card > as unusable. Consequently, it abandons entire sound card, including > other valid audio sinks. I have also started discussing this issue with > pipewire [1] > > > What is the expected pcm device behavior when DP jack is not connected? > > Two possibilities: > > 1. Consume the data even when the Display is not connected. I see that > in Intel case it sinks the data somewhere and gives the user an > experience that the data is getting consumed. > > 2. Throw an error to user if they attempt to configure or send the data > to this disconnected pcm. > > > Also what userspace ABI to for such usecase? > > This is blocking end-to-end DP audio enablement on Qualcomm SoCs. > > Not sure if this is right approach or will work but somehow we back the > pcm devices with disconnected jack state to use dummy pcm ops instead of > actual pcm ops? > This should at least keep the pipewire happy. Is this the right approach? > > > [1]: https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/4938 > > Thanks, > Srini I believe this has been a long-standing problem even for HD-audio. The HD-audio HDMI driver does open and process without actual pin setup for allowing the probe by PA/PW with the assumption of some basic PCM parameters. It was introduced in the commit 42b2987079eca0238b576c08af1144ed5bd52188 ALSA: hda - hdmi playback without monitor in dynamic pcm bind mode So I find using a dummy ops would make sense (assuming it's actually enough to convince PA/PW). thanks, Takashi