From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: [PATCH]snd-usb-usx2y 0.8.7: Use macro usb_maxpacket() for portability Date: Thu, 09 Dec 2004 11:14:02 +0100 Message-ID: References: <200412021319.20027.annabellesgarden@yahoo.de> <200412062315.01880.annabellesgarden@yahoo.de> <200412072301.52065.annabellesgarden@yahoo.de> Mime-Version: 1.0 (generated by SEMI 1.14.5 - "Awara-Onsen") Content-Type: text/plain; charset=US-ASCII 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: Jaroslav Kysela Cc: Karsten Wiese , alsa-devel@lists.sourceforge.net List-Id: alsa-devel@alsa-project.org At Thu, 9 Dec 2004 09:18:04 +0100 (CET), Jaroslav wrote: > > On Wed, 8 Dec 2004, Takashi Iwai wrote: > > > At Tue, 7 Dec 2004 23:01:51 +0100, > > Karsten Wiese wrote: > > > > > > >>>> > > > Summary: hwdep interface for pcm data. > > > > > > Implements "rawusb" pcm data transfer through hwdep interface: > > > The usb_hc moves pcm data from/into memory via DMA. > > > That memory is mmaped by jack's usx2y driver. > > > Jack's usx2y driver is the first/last executable code to read/write pcm data. > > > Read/write is a combination of power of 2 period shaping and float/int conversation. > > > Compared to standard alsa/jack we leave out power of 2 period shaping > > > inside snd-usb-usx2y which needs memcpy() and additional buffers. > > > As a side effect possible unwanted pcm-data coruption resulting of > > > standard alsa's snd-usb-usx2y period shaping scheme falls away. > > > Result is sane jack operation at buffering schemes down to 128frames, 2 periods. > > > Also changed Kconfig file, so snd-usb-usx2y is only available for X86, PPC or ALPHA platforms, > > > as on others DMA-memory isn't mmapable. > > > > > > Signed-off-by: Karsten Wiese > > > <<<< > > > > Thanks, applied to the CVS tree now. > > Please check later whether it works for you... > > My feeling is that it's against all we're trying to do with the PCM > interface. Cannot we extend/optimize the current PCM API? Don't worry, in the new patch, the hwdep does actually only mmap. The others are done with the usual PCM API. The implementation is still a bit tricky, IMO, though. We can generalize this if there would be more wide needs for such stuff. Takashi ------------------------------------------------------- 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://productguide.itmanagersjournal.com/