Date: Tue, 17 Apr 2007 08:47:15 +0200 From: usleepless@gmail.com To: "John-Mark Gurney" <gurney_j@resnet.uoregon.edu>, usleepless@gmail.com, "Greg 'groggy' Lehey" <grog@freebsd.org>, freebsd-multimedia@freebsd.org Subject: Re: pvrxxx, linux code and modules Message-ID: <c39ec84c0704162347x31eb76acs6f971a85142559b4@mail.gmail.com> In-Reply-To: <20070417001817.GZ73385@funkthat.com> References: <c39ec84c0704151508t126cf975gaa1957b9205d3244@mail.gmail.com> <20070416055055.GC1593@wantadilla.lemis.com> <20070416212605.GV73385@funkthat.com> <c39ec84c0704161551i29914e70vd78f725f765c0c04@mail.gmail.com> <20070417001817.GZ73385@funkthat.com>
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John-Mark, On 4/17/07, John-Mark Gurney <gurney_j@resnet.uoregon.edu> wrote: > usleepless@gmail.com wrote this message on Tue, Apr 17, 2007 at 00:51 +0200: > > On 4/16/07, John-Mark Gurney <gurney_j@resnet.uoregon.edu> wrote: > > >Greg 'groggy' Lehey wrote this message on Mon, Apr 16, 2007 at 15:20 > +0930: > > >> - I need to understand better how tuners work. I've been thinking of > > >> writing a document on the subject, something that people could use > > >> for help when writing drivers. If you know of anything, even > > >> partial or badly laid out, please let me know. > > > > > >Just to reiterate, tuner code really should be located in userland.. > > >it's not time sensitive, and can't corrupted state of the kernel.. > > > > > >As for tuners, most/all of them communicate through the i2c bus... > > >The tuner is programed w/ the frequency to tune, and depending upon > > >the range of frequence will turn on/off various transistors to change > > >some of the analog curcuit behavior... > > > > > >My HDTV device drive does all the tuning from userland... > > > > which driver is this? > > The DViCO FusionHDTV 5 Lite driver: > http://www.freebsd.org/news/status/report-2006-10-2006-12.html#Bt878-Audio-Driver-(aka-FusionHDTV-5-Lite-driver) > > I have two tuners working in my system at home. how does one build this driver? where can i fetch it? > > >It was > > >a lot easier to get it working using userland than having to constantly > > >load/unload kernel modules, and risk crashing the machine... > > > > you are absolutely spot on about this. it's that i did build upon > > pvr250 which had the tuner in kernel space, so i didn't think about > > it. otherwise i might have been influenced by the linux source, and i > > would have implemented in kernel space as well :-) > > > > but considering V4L(2), which has to support ioctl's changing the > > frequency, how could this work from userland? > > Kill the V4L(2) API? :) I have thought about doing a cdev bridge to > userland.. Effectively FUSE, but for cdev's instead of file systems... > This would put most/all the logic in userland, and w/ some mmapping > magic, can have similar/same performance for high speed devices like > bktr... well, i am certainly not gonna kill the v4l(2) API since i intend to use the pvrxxx cards with mythtv. regards, usleep
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