From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <5171700A.50308@ladisch.de> Date: Fri, 19 Apr 2013 18:25:46 +0200 From: Clemens Ladisch MIME-Version: 1.0 References: In-Reply-To: Subject: Re: [alsa-devel] BUG: USB audio discontinuities with 'UHCI: implement new semantics for URB_ISO_ASAP' List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: alsa-devel@alsa-project.org Cc: tova-dev@tovacompany.com, linux-usb@vger.kernel.org, Joe Rayhawk , alsa-devel@vger.kernel.org List-ID: Alan Stern wrote: > ... > This trace shows that the frame numbers do not increase sequentially: > 1057125, 1057126, 1057128, 1057129, 1053131, ... This is because the > new driver is a little more conservative than the old driver, > requiring latencies to be larger than 1 ms. You can see this > explicitly in one of the new lines added by the commit you found: > > + next = uhci->frame_number + 2; > > That 2 is the minimum latency, in frames (one frame per ms). One frame worked fine with the old driver. What is the reason for this regression? > Anyway, the solution is simple: The audio driver needs either to submit > buffers that are at least 2 ms long, or to use more than two buffers > (or both). The audio driver already has the infrastructure to cope for hardware restrictions like this, it just needs to *know* about them. How can it detect that it runs on the OHCI/UHCI drivers? Regards, Clemens -- To unsubscribe from this list: send the line "unsubscribe alsa-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel