From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Date: Thu, 16 Jun 2011 15:02:59 +0000 Subject: Re: [PATCH] udev: Allow ALSA input jacks to be accessed by the current user Message-Id: List-Id: References: <4DFA0F40.7000204@canonical.com> In-Reply-To: <4DFA0F40.7000204@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-hotplug@vger.kernel.org At Thu, 16 Jun 2011 16:55:39 +0200, Kay Sievers wrote: > > On Thu, Jun 16, 2011 at 16:48, Takashi Iwai wrote: > > At Thu, 16 Jun 2011 16:28:08 +0200, > > Kay Sievers wrote: > >> > >> On Thu, Jun 16, 2011 at 16:12, David Henningsson > >> wrote: > >> > One missing piece for userspace (PulseAudio etc) to actually be able to use > >> > the jack input devices that ALSA create, is that these devices are > >> > accessible by root only. This patch makes the input device nodes accessible > >> > by the same users that can access the sound card: the current logged in > >> > user, as well as users in the audio group. > >> > > >> > One thing I was thinking about, was that the udev-acl rule actually grants > >> > read-write access to the input device node, where probably only read access > >> > is needed. Is this dangerous? > >> > >> Takashi, wasn't there already something else to use from ALSA than the > >> artificial input devices? > > > > These input devices are just notification from the sound driver at > > jack plugging, so basically it's read-only indeed, and setting the > > file permission RO would make sense. > > Na, I mean, I remember you talking about some other channel of > notifications about jack changes. Ah, yeah, it's still possible to implement via ALSA control API, too. Just add a new control element for jack notification, and the apps can listen to it via normal ALSA API like the mixer elements. > Didn't the input devices get replaced by something on the control > device? Or was that just a plan? I had some patches for it years ago, but never got merged. If apps prefer it, I can revisit it. Meanwhile, the jack-input stuff is already present, so it might not be worth for it. Takashi