I spent my money - but wish I'd researched first. The following from LKML Greg K-H says it all....
On Fri, Jan 11, 2013 at 04:10:30PM +0200, Ozan ÃaÄYlayan wrote:
> > Ah, my sympathies, USB on a rpi is horrible, and you will have all sorts
> > of nasty issues, no matter how you end up doing this (in the kernel or
> > userspace).
>
> What kind of issues? Currently I can read from the device without
> problem. But, I had very weird problems with 2 uvc cameras, you're
> right.
High cpu usage is one problem, and low overall USB bandwidth is another,
combined with slow response times. The hardware really is bad for USB,
and the driver is a whole other beast, something that no one in the
community can, or will, touch at all.
> > Test it out and see. I really don't think that user vs. kernel space is
> > going to be the issue here, I think you are going to see some very real
> > problems with the hardware itself in this area.
> >
> > Best of luck,
>
> Well If I were you I would probably write that simple driver in a few
> hours but seen that I am not you, I wanted to learn will the effort
> worth the result:)
It all depends on what you want to do, but I really think that user vs.
kernelspace is not going to be the real problem here. Start with libusb
and if you find that you are having problems, use 'perf' to see if the
kernel part is really the problem. I think you will find all of your
time is going to be spent in the USB hardware itself, and the USB
driver, once you get the data out of that, user vs. kernel is not going
to be noticable at all.
Best of luck, and I bet you, in the end, you pick a better hardware
platform for your project (hint, go buy a Beaglebone, it actually works
and the tiny increase in cost more than makes up for the time you will
waste fighting the RPI hardware.)
greg k-h
--
I get my Linux kernel as a source - that is not a "package" - there is a BIG difference between "Linux" and "distributions built on top of Linux". You absolutely do not have to use packages to use Linux...
Who the hell mod'ed this informative - Linux is the "base system" (you know - the kernel?) and then you pile all the other stuff on top (via packages, source, or whatever method floats your boat)
Boeing are becoming "expert" in assembling aircraft components. But like many, many companies they are suffering from a severe lack of quality engineers to innovate and drive the company forwards in engineering. And as the baby-boomers continue to retire it is getting progressively worse. The up-and-coming "stars" with their shinny new degrees just can not cut it...
People figured out how the space shuttle blew into a billion fragments, but the "best" aerospace company in the world can't figure out why a couple of batteries went into meltdown...
The Peter Principle: http://en.m.wikipedia.org/wiki/Peter_Principle . I'd never heard of that principle under that name, but I've come across it often enough in academia and in "real work" places.
You're absolutely wrong! The focus should be on "educating" children to learn how to self-discover and self-learn using this low cost device. Spoon feeding some government sponsored syllabus is not going to achieve that.
The point is that "the UK government has stated there is no place in the science curriculum for Intelligent Design and that it can not be taught as science." Finally, this government has pulled its head out of its own politically correct asshole, spoken the thoughts of the vast majority of the people that democraticslly elected them to power and stopped pandering to the small-minded lobby groups.
Still, it's all too little, too late. I can't wait until they loose the next election...
Port all your apps to VMS! Then every file save will have a version number.
e.g.
edit filename.txt
file saved as filename.txt;1
edit filename.txt
file saved as filename.txt;2
These revisions contain the whole file - not some undecipherable unix "diff" increment.
I remember the first time the desktop welcome sound came from my speakers with a clean Linux install - I nearly crapped myself with fear! After 4 years of no sound on my Linux partition - it came as a bit of a shock.
Slashdot Mirror
VaxVmsAmp. I've been waiting so long for that...
I spent my money - but wish I'd researched first. The following from LKML Greg K-H says it all.... On Fri, Jan 11, 2013 at 04:10:30PM +0200, Ozan ÃaÄYlayan wrote: > > Ah, my sympathies, USB on a rpi is horrible, and you will have all sorts > > of nasty issues, no matter how you end up doing this (in the kernel or > > userspace). > > What kind of issues? Currently I can read from the device without > problem. But, I had very weird problems with 2 uvc cameras, you're > right. High cpu usage is one problem, and low overall USB bandwidth is another, combined with slow response times. The hardware really is bad for USB, and the driver is a whole other beast, something that no one in the community can, or will, touch at all. > > Test it out and see. I really don't think that user vs. kernel space is > > going to be the issue here, I think you are going to see some very real > > problems with the hardware itself in this area. > > > > Best of luck, > > Well If I were you I would probably write that simple driver in a few > hours but seen that I am not you, I wanted to learn will the effort > worth the result :)
It all depends on what you want to do, but I really think that user vs.
kernelspace is not going to be the real problem here. Start with libusb
and if you find that you are having problems, use 'perf' to see if the
kernel part is really the problem. I think you will find all of your
time is going to be spent in the USB hardware itself, and the USB
driver, once you get the data out of that, user vs. kernel is not going
to be noticable at all.
Best of luck, and I bet you, in the end, you pick a better hardware
platform for your project (hint, go buy a Beaglebone, it actually works
and the tiny increase in cost more than makes up for the time you will
waste fighting the RPI hardware.)
greg k-h
--
$640K ought to be enough for anybody. /*
Sent from my iPhone
*/
I get my Linux kernel as a source - that is not a "package" - there is a BIG difference between "Linux" and "distributions built on top of Linux". You absolutely do not have to use packages to use Linux...
Who the hell mod'ed this informative - Linux is the "base system" (you know - the kernel?) and then you pile all the other stuff on top (via packages, source, or whatever method floats your boat)
"... BSD has released version ..." ...and nobody gives a fuck. And the world keeps spinning...
The design "flew" for hundreds of thousands of hours on the desktop simulation without any problems;-)
Boeing are becoming "expert" in assembling aircraft components. But like many, many companies they are suffering from a severe lack of quality engineers to innovate and drive the company forwards in engineering. And as the baby-boomers continue to retire it is getting progressively worse. The up-and-coming "stars" with their shinny new degrees just can not cut it...
People figured out how the space shuttle blew into a billion fragments, but the "best" aerospace company in the world can't figure out why a couple of batteries went into meltdown...
The Peter Principle: http://en.m.wikipedia.org/wiki/Peter_Principle . I'd never heard of that principle under that name, but I've come across it often enough in academia and in "real work" places.
You're absolutely wrong! The focus should be on "educating" children to learn how to self-discover and self-learn using this low cost device. Spoon feeding some government sponsored syllabus is not going to achieve that.
The point is that "the UK government has stated there is no place in the science curriculum for Intelligent Design and that it can not be taught as science." Finally, this government has pulled its head out of its own politically correct asshole, spoken the thoughts of the vast majority of the people that democraticslly elected them to power and stopped pandering to the small-minded lobby groups. Still, it's all too little, too late. I can't wait until they loose the next election...
I just pissed my pants. Take a $20 keyboard, scrub the print off the keys and sell it for $90. What fucking morons buy this shit?
'xine' - I've been pronouncing it z-eye-n. No wonder I have been getting stange looks from the multimedia geeks around here.
whilst Linux is undoubtedly good, I used it for my MSCE exams and got a "Grade F". Using Linux is not a guaranteed method of getting an "A".
Port all your apps to VMS! Then every file save will have a version number. e.g. edit filename.txt file saved as filename.txt;1 edit filename.txt file saved as filename.txt;2 These revisions contain the whole file - not some undecipherable unix "diff" increment.
I remember the first time the desktop welcome sound came from my speakers with a clean Linux install - I nearly crapped myself with fear! After 4 years of no sound on my Linux partition - it came as a bit of a shock.
I Piled it Higher and Deeper in Artificial Neural Networks - nothing funny in that
...humorous mnemonic "Three out of every two stars is a binary". humorous????? Get a life