From mboxrd@z Thu Jan 1 00:00:00 1970 From: Manuel Jander Subject: Re: Re: Re: au8830 - front / rear channels swapped after first play and Surround40 Date: Thu, 17 Mar 2005 10:45:39 -0400 Message-ID: <1111070739.3269.4.camel@localhost> References: <4238F81C.30405@netvigator.com> Reply-To: mjander@users.sourceforge.net Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit In-Reply-To: <4238F81C.30405@netvigator.com> Sender: alsa-devel-admin@lists.sourceforge.net Errors-To: alsa-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Raymond , alsa-devel List-Id: alsa-devel@alsa-project.org Hi Raymond, On Thu, 2005-03-17 at 11:23 +0800, Raymond wrote: > > > No, thats not a bug. Thats normal. > > > > > > AFAIK the FIFO error occurs only one time, the first time data is > > being DMA'ed. It could be that this error is some kind of data > > underrun, and it does only happen once, because we never flush the > > FIFO's when stopping a stream. Remaining data in the FIFO's may be > > messing the channel deinterlacer, because the amount of data loaded in > > the fifo is random, generating a random offset. Since the the PCI bus > > is 32 bit wide, that problem would not affect stereo streams, because > > one 32 bit transaction maps to two 16 bit samples. Only where a frame > > is more that 32bits, this problem would become apparent. This is just > > a theory, but maybe it could be worth a try, to enforce a absolute > > flush of the FIFO data when stopping a DMA stream. > > The "vortex: IRQ fifo error" message happen once when the first play is > a stereo or 4 channels sound and it do not happen when the first play is > a MONO sound on my au8830. > > Using "vortex_adbdma_stopfifo()" instead of vortex_adbdma_pausefifo()" > in snd_vortex_pcm_trigger() (just like the last version of au88x0 in > alsa-driver before it merged into alsa-kernel) seem to fix the > front/rear channels swap when playing 4 channels sound in au8830. Using "vortex_adbdma_stopfifo" sounds more reasonable to me, regarding of what i explained above. > However the message "vortex: IRQ fifo error" will appear more than once > in the kernel log, it is quite annoying when a lot of these message is > displayed on the screen (not always) during the shutdown of the linux. Does the IRQ fifo error appear once for every sound played or a lot more than that ? if it appears once for every PCM plaayback start, it may be that this error is just a harmless "fifo empty" error, and as such could be just ignored. An if it really signals a FIFO empty error, it maybe useful to detect xruns ? Best Regards, -- Manuel Jander Electronic Engineer ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click