Date: Mon, 7 Mar 2005 11:57:42 +0900 From: Pyun YongHyeon <yongari@kt-is.co.kr> To: Mathew Kanner <mat@cnd.mcgill.ca> Cc: freebsd-multimedia@freebsd.org Subject: Re: uaudio patch, configurable buffer size Message-ID: <20050307025742.GA951@kt-is.co.kr> In-Reply-To: <20050305224005.GC4237@cnd.mcgill.ca> References: <20050305224005.GC4237@cnd.mcgill.ca>
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On Sat, Mar 05, 2005 at 05:40:05PM -0500, Mathew Kanner wrote: > Hi All, > I couldn't use my usb device because the default buffer size > (16*1024 bytes) was too much to be allocated (dma changes that > happened a while ago). The following is a patch to make it a tunable: > > http://www.cnd.mcgill.ca/~mat/uaudio-HEAD-buffersize-tunable.diff.gz > Hi Mathew, I guess the real reason DMA buffer allocation failure comes from the fixed argument 0x3fff of bus_dma_tag_create(9). And if we allow TUNABLE for "hw.snd.uaudio.default_buffer_size" we should also update the argument of bus_dma_tag_create(9) too or we couldn't allocate larger buffer size than 16383(0x3fff). Another thing to note is that we are not allowed to use buffer size less than 4KB since we use bufsz = pcm_getbuffersize(dev, 4096, UAUDIO_PCM_BUFF_SIZE, 65536); in uaudio_pcm.c. So I think you should also reject size less than 4KB. -- Regards, Pyun YongHyeon http://www.kr.freebsd.org/~yongari | yongari@freebsd.org
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