From mboxrd@z Thu Jan 1 00:00:00 1970 From: "M. Nentwig" Subject: Hammerfall DSP: Midi-related audio dropouts workaround / question Date: Fri, 15 Nov 2002 08:45:33 +0200 Sender: alsa-devel-admin@lists.sourceforge.net Message-ID: <3DD4980D.8C70735B@users.sourceforge.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Errors-To: alsa-devel-admin@lists.sourceforge.net List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: To: paul@linuxaudiosystems.com Cc: alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org Hello, a couple of days I wrote about audio dropouts caused by MIDI data. Now I found a workaround: Unloading the uhci (USB) driver, loading the hammerfall driver, reloading the uhci driver gets rid of the dropouts. Also plugging in a USB device helps. Both USB controller and hdsp share the same interrupt on my laptop. Before I found this workaround, I spent some time hacking the hdsp driver. I created a new thread, that sleeps ('interruptible_sleep_on(sth)'), until the MIDI interrupt wakes it ('wake_up'(sth)). As long as it's doing no real work (just counting MIDI events for example), everything works fine. But as soon as I take the MIDI processing out of the interrupt (or remove it completely), the machine locks up. Probably during the interrupt - even the 'magic sysrq key' is dead. And I don't understand this at all. Does the hardware crash, if I don't empty the MIDI FIFO queue in time? The crash occurs also, when MIDI processing is removed from a vanilla hdsp driver. Some related observations: - The dropouts disappear, if I disable MIDI interrupts. But then MIDI in is unreliable, big surprise. - The dropouts don't get any better, if I don't submit the received data to alsa at the end of the MIDI-in processing. Regards Markus ------------------------------------------------------- This sf.net email is sponsored by: To learn the basics of securing your web site with SSL, click here to get a FREE TRIAL of a Thawte Server Certificate: http://www.gothawte.com/rd524.html