Date: Tue, 17 Apr 2007 00:51:37 +0200 From: usleepless@gmail.com To: "John-Mark Gurney" <gurney_j@resnet.uoregon.edu>, "Greg 'groggy' Lehey" <grog@freebsd.org>, usleepless@gmail.com, freebsd-multimedia@freebsd.org Subject: Re: pvrxxx, linux code and modules Message-ID: <c39ec84c0704161551i29914e70vd78f725f765c0c04@mail.gmail.com> In-Reply-To: <20070416212605.GV73385@funkthat.com> References: <c39ec84c0704151508t126cf975gaa1957b9205d3244@mail.gmail.com> <20070416055055.GC1593@wantadilla.lemis.com> <20070416212605.GV73385@funkthat.com>
next in thread | previous in thread | raw e-mail | index | archive | help
John, 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? > 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? regards, usleep
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?c39ec84c0704161551i29914e70vd78f725f765c0c04>