From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian McMenamin Subject: Re: pointer callback in pcm Date: Fri, 10 Mar 2006 20:21:07 +0000 Message-ID: <1142022067.9246.7.camel@localhost.localdomain> References: <1141942882.10937.5.camel@localhost.localdomain> <1141952015.13319.90.camel@mindpipe> <1142020261.9246.3.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: 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: Takashi Iwai Cc: Lee Revell , alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org On Fri, 2006-03-10 at 21:16 +0100, Takashi Iwai wrote: > > Hm, I've not checked your code and thread due to lack of my free time > for ALSA recently, but the symptom above sounds like you implemented > copy callback but still using mmap. > No, I'm not using copy or mmap (the code is at http://newgolddream.dyndns.info/cgi-bin/cvsweb these days) > The copy callback is designed basically only for read/write transfer. > In the mmap mode, of course, such read/write transfer is eliminated, > and no copy action occurs. > > Thus, first try not to set MMAP flag and let alsa-lib use the > traditional read/write method. > > Some hardwares have actually separate h/w buffer and the memory > buffer (s/w buffer). Even with such hardwares, mmap can be > implemented. Instead of DMA transfer by hardware, the driver copies > data between h/w and s/w buffers on demand, namely, before starting > the stream (in trigger callback) and when each period is consumed (via > ack callback). This is quite like my device - but I know nothing about the ack device > > There are userful functions for such a case, found in pcm-indirect.h. > They are used emu10k1 FX mode and cs46xx. > I'll look > > HTH, > > Takashi ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642