From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: [RFC PATCH] ASoC: codec: hdac_hdmi: no checking monitor in hw_params Date: Mon, 06 May 2019 17:41:08 +0200 Message-ID: References: <1557125960-29353-1-git-send-email-libin.yang@intel.com> Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 0BE48F896F0 for ; Mon, 6 May 2019 17:41:09 +0200 (CEST) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" To: Pierre-Louis Bossart Cc: libin.yang@intel.com, alsa-devel@alsa-project.org, broonie@kernel.org, subhransu.s.prusty@intel.com, samreen.nilofer@intel.com List-Id: alsa-devel@alsa-project.org On Mon, 06 May 2019 17:37:32 +0200, Pierre-Louis Bossart wrote: > > On 5/6/19 1:59 AM, libin.yang@intel.com wrote: > > From: Libin Yang > > > > This patch move the check of monitor from hw_params to trigger callback. > > > > The original code will check the monitor presence in hw_params. If the > > monitor doesn't exist, hw_params will return -ENODEV. Mostly this is OK. > > > > However, pulseaudio will check the pcm devices when kernel is booting up. > > It will try to open, set hw_params, prepare such pcm devices. We can't > > guarantee that the monitor will be connected when kernel is booting up. > > Especially, hdac_hdmi will export 3 pcms at most. It's hard to say users > > will connect 3 monitors to the HDMI/DP ports. This will cause pulseaudio > > fail in parsing the pcm devices because the driver will return -ENODEV in > > hw_params. > > > > This patch tries to move the check of monitor presence into trigger > > callback. This can "trick" the pulseaudio the pcm is ready. > > > > This bug is found when we try to enable HDMI detection in > > gnome-sound-setting for ASoC hdac_hdmi. After we enable the hdmi in UCM, > > pulseaudio will try to parse the hdmi pcm devices. It will cause failure if > > there are no monitors connected. > > Out of curiosity, how is this handled in the legacy driver? I haven't > done this for a long time but I remember very clearly being able to > play on the HDMI:3,7, etc devices without any monitors > connected. You'd get of course no sound but there was no error > reported to userspace. The hardware is perfectly capable of pushing > samples into the display controller using the HDAudio/iDisp link. As mentioned in the thread, PA just picks up the stream that is connected via a monitor by checking / notified by the corresponding Jack control. On hdac_hdmi driver, the jack control has different base name that is irrelevant with the output pins, so PA doesn't know how to interpret it, hence it's ignored. thanks, Takashi