From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Courtier-Dutton Subject: Re: USB disconnect/connect messages Date: Mon, 21 Jul 2003 19:03:29 +0100 Sender: alsa-devel-admin@lists.sourceforge.net Message-ID: <3F1C2AF1.1030106@superbug.demon.co.uk> References: <3F1B2870.3070505@superbug.demon.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Errors-To: alsa-devel-admin@lists.sourceforge.net List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: To: Takashi Iwai Cc: alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org Takashi Iwai wrote: > At Mon, 21 Jul 2003 00:40:32 +0100, > James Courtier-Dutton wrote: > >>Hi, >> >>Is there any way to tell if a USB sound card has been disconnected or not? > > > IIRC, this is not notified to the application. > the app simply would get an error at the further access. > it sounds not bad to notify the status change to the application by > some way. > perhaps we can add a new control element for this purpose. > and after disconnection, only this element survives to communicate > with the application... > So, the app gets an error. Which error? How do I test to see if the error is due to a non-existant device, or just underrun/overrun etc. I would be happy if there was a reliable way to tell. This would only give us the "disconnect" event. How would one know if the device was connected again? Maybe a tidy way to do this would be a new alsa events device. So, we open the "events" device, and it can then inform us of hardware changes. I know that USB is the only form of device that connects/disconnects via a user action at the moment, but I am sure others will come along. E.g. Bluetooth etc. For USB, usbaudio.c definitely gets informed about usb device removal/addition, how can we get that message passed up to the application? Cheers James ------------------------------------------------------- This SF.net email is sponsored by: VM Ware With VMware you can run multiple operating systems on a single machine. WITHOUT REBOOTING! Mix Linux / Windows / Novell virtual machines at the same time. Free trial click here: http://www.vmware.com/wl/offer/345/0