Mailing List Archive: Gentoo: User

Running a USB graphics cards with Linux?

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sping at gentoo

Feb 14, 2012, 2:19 PM

Post #1 of 9 (918 views)
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Running a USB graphics cards with Linux?

Hello,

I would love to use two external displays with my notebook. I have seen
USB graphics cards on the net and was wondering if anyone around here
has tried to run such a thing with Linux. If it worked for you I'd be
interested in as many details as you are willing to share. Thanks in
advance!

Best,

Sebastian

pinklotus at gmx

Feb 15, 2012, 12:14 PM

Post #2 of 9 (906 views)
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Re: Running a USB graphics cards with Linux? [In reply to]

Am Dienstag, 14. Februar 2012, 23:19:56 schrieb Sebastian Pipping:
> Hello,
>
>
> I would love to use two external displays with my notebook. I have seen
> USB graphics cards on the net and was wondering if anyone around here
> has tried to run such a thing with Linux. If it worked for you I'd be
> interested in as many details as you are willing to share. Thanks in
> advance!
>
> Best,
>
>
>
> Sebastian

Hallo
I used one some time ago, and it worked but very slow.
The label only says made in China.
lsusb output is:
Bus 001 Device 004: ID 0711:0900 Magic Control Technology Corp. SVGA Adapter
The Kernel module which is loaded is:
sisusbvga
If your interested in the dongle and you live somewhere around Germany, I can
send it to you, because I don't need it anymore.

greatings

günter

--

sping at gentoo

Jul 15, 2012, 3:54 PM

Post #3 of 9 (820 views)
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Re: Running a USB graphics cards with Linux? [In reply to]

Hi there,

On 02/15/2012 09:14 PM, gk wrote:
> Hallo
> I used one some time ago, and it worked but very slow.
> The label only says made in China.
> lsusb output is:
> Bus 001 Device 004: ID 0711:0900 Magic Control Technology Corp. SVGA Adapter
> The Kernel module which is loaded is:
> sisusbvga
> If your interested in the dongle and you live somewhere around Germany, I can
> send it to you, because I don't need it anymore.

I'm afraid if it's slow I do not have much real use for it. Many thanks
for the offer, though! And sorry for the ages that it took to reply.

Best,

Sebastian

mikemol at gmail

Jul 15, 2012, 5:24 PM

Post #4 of 9 (818 views)
Permalink

Re: Running a USB graphics cards with Linux? [In reply to]

On Sun, Jul 15, 2012 at 6:54 PM, Sebastian Pipping <sping [at] gentoo> wrote:
> Hi there,
>
>
> On 02/15/2012 09:14 PM, gk wrote:
>> Hallo
>> I used one some time ago, and it worked but very slow.
>> The label only says made in China.
>> lsusb output is:
>> Bus 001 Device 004: ID 0711:0900 Magic Control Technology Corp. SVGA Adapter
>> The Kernel module which is loaded is:
>> sisusbvga
>> If your interested in the dongle and you live somewhere around Germany, I can
>> send it to you, because I don't need it anymore.
>
> I'm afraid if it's slow I do not have much real use for it. Many thanks
> for the offer, though! And sorry for the ages that it took to reply.

Unfortunately, you're probably not going to find anything for USB
which _isn't_ slow. USB is a very slow bus when compared to HDMI, DVI
or VGA.

--
:wq

kilian at diezotts

Jul 17, 2012, 7:03 AM

Post #5 of 9 (821 views)
Permalink

Re: Running a USB graphics cards with Linux? [In reply to]

thats a strange comparison since usb is a serial bus
vga is not even digital, so how can you talk about throughput? lol

2012/7/16 Michael Mol <mikemol [at] gmail>

> On Sun, Jul 15, 2012 at 6:54 PM, Sebastian Pipping <sping [at] gentoo>
> wrote:
> > Hi there,
> >
> >
> > On 02/15/2012 09:14 PM, gk wrote:
> >> Hallo
> >> I used one some time ago, and it worked but very slow.
> >> The label only says made in China.
> >> lsusb output is:
> >> Bus 001 Device 004: ID 0711:0900 Magic Control Technology Corp. SVGA
> Adapter
> >> The Kernel module which is loaded is:
> >> sisusbvga
> >> If your interested in the dongle and you live somewhere around Germany,
> I can
> >> send it to you, because I don't need it anymore.
> >
> > I'm afraid if it's slow I do not have much real use for it. Many thanks
> > for the offer, though! And sorry for the ages that it took to reply.
>
> Unfortunately, you're probably not going to find anything for USB
> which _isn't_ slow. USB is a very slow bus when compared to HDMI, DVI
> or VGA.
>
> --
> :wq
>
>

frares at gmail

Jul 17, 2012, 7:18 AM

Post #6 of 9 (818 views)
Permalink

Re: Re: Running a USB graphics cards with Linux? [In reply to]

Em , Kilian Zott <kilian [at] diezotts> escreveu:
> thats a strange comparison since usb is a serial busvga is not even
> digital, so how can you talk about throughput? lol

> 2012/7/16 Michael Mol mikemol [at] gmail>

> On Sun, Jul 15, 2012 at 6:54 PM, Sebastian Pipping sping [at] gentoo>
> wrote:

> > Hi there,
> >
> >
> > On 02/15/2012 09:14 PM, gk wrote:
> >> Hallo
> >> I used one some time ago, and it worked but very slow.
> >> The label only says made in China.
> >> lsusb output is:
> >> Bus 001 Device 004: ID 0711:0900 Magic Control Technology Corp. SVGA
> Adapter
> >> The Kernel module which is loaded is:
> >> sisusbvga
> >> If your interested in the dongle and you live somewhere around
> Germany, I can
> >> send it to you, because I don't need it anymore.
> >
> > I'm afraid if it's slow I do not have much real use for it. Many thanks
> > for the offer, though! And sorry for the ages that it took to reply.
> >

> Unfortunately, you're probably not going to find anything for USB
> which _isn't_ slow. USB is a very slow bus when compared to HDMI, DVI
> or VGA.

> --

> :wq

Well, thinkig a bit, even on a non digital interface, as you have those
vertical and horizontal frequencies for each video mode, I guess one can
talk like "pixels per second" using some math on those numbers.

Francisco

kilian at diezotts

Jul 17, 2012, 7:32 AM

Post #7 of 9 (821 views)
Permalink

Re: Re: Running a USB graphics cards with Linux? [In reply to]

You could compare the frame rate, but an analog signal cant be compared to
a digital signal ^^
if you resolute your analog voltage in 8 bit (256 steps each subpixel, so
24bit color depth) you get some offset on the transmission
so you could not use an analog interface in order to transmit data (there
would only trash arrive)!
and there is no error correction either.

next thing is that the usb interface is not between the screen and the
graphics card but between the mainboard and the graphics card
there is no video transmission at this place!
it would be more sensible to compare usb to pci-e or agp.

2012/7/17 <frares [at] gmail>

> Em , Kilian Zott <kilian [at] diezotts> escreveu:
> > thats a strange comparison since usb is a serial busvga is not even
> digital, so how can you talk about throughput? lol
>
> >
> >
> > 2012/7/16 Michael Mol mikemol [at] gmail>
> >
> > On Sun, Jul 15, 2012 at 6:54 PM, Sebastian Pipping sping [at] gentoo>
> wrote:
> >
> > > Hi there,
> > >
> > >
> > > On 02/15/2012 09:14 PM, gk wrote:
> > >> Hallo
> > >> I used one some time ago, and it worked but very slow.
> > >> The label only says made in China.
> > >> lsusb output is:
> > >> Bus 001 Device 004: ID 0711:0900 Magic Control Technology Corp. SVGA
> Adapter
> > >> The Kernel module which is loaded is:
> > >> sisusbvga
> > >> If your interested in the dongle and you live somewhere around
> Germany, I can
> > >> send it to you, because I don't need it anymore.
> > >
> > > I'm afraid if it's slow I do not have much real use for it. Many
> thanks
> > > for the offer, though! And sorry for the ages that it took to reply.
> > >
>
> >
> > Unfortunately, you're probably not going to find anything for USB
> > which _isn't_ slow. USB is a very slow bus when compared to HDMI, DVI
> > or VGA.
> >
> > --
> >
> > :wq
> >
> >
> >
>
> Well, thinkig a bit, even on a non digital interface, as you have those
> vertical and horizontal frequencies for each video mode, I guess one can
> talk like "pixels per second" using some math on those numbers.
>
> Francisco

mikemol at gmail

Jul 17, 2012, 7:50 AM

Post #8 of 9 (818 views)
Permalink

Re: Running a USB graphics cards with Linux? [In reply to]

On Tue, Jul 17, 2012 at 10:03 AM, Kilian Zott <kilian [at] diezotts> wrote:
> thats a strange comparison since usb is a serial bus
> vga is not even digital, so how can you talk about throughput? lol

Information doesn't need to be digital. Terms like 'bandwidth' really do apply.

VGA does place some structure on its signal. You have a vertical and
horizontal refresh rates. Your vertical refresh rate is usually in the
10s of Hz. I've seen displays range from 56Hz (terrible, terrible
flicker on CRTs) to 120Hz (smooth as glass). Your horizontal refresh
rates are usually in the 10s of *KHz*.

The combination of the two dictated how many scanlines you could fit
into your signal. Your number of pixels in a line was (in reality)
limited by your video card's dot clock, but you might adjust things if
you preferred, e.g. square pixels instead of whatever the per-pixel
aspect ratio normally was. (I really don't rememeber.)

Unlike DVI and HDMI, which support pixel formats that have
subsampling, VGA didn't have any kind of compression mechanism. You
had three channels, red, green and blue, and their voltage levels on
the wire controlled the brightness of that color at whatever
particular point on the display corresponded to that instant in your
horizontal and vertical sweeps.

If you'd like to know how I compare USB and VGA, look at ways VGA and
DVI are analogous. Of course, under certain (now very unusual)
circumstances, VGA can kick DVI's butt.

--
:wq

mikemol at gmail

Jul 17, 2012, 7:51 AM

Post #9 of 9 (823 views)
Permalink

Re: Re: Running a USB graphics cards with Linux? [In reply to]

On Tue, Jul 17, 2012 at 10:32 AM, Kilian Zott <kilian [at] diezotts> wrote:
> You could compare the frame rate, but an analog signal cant be compared to a
> digital signal ^^
> if you resolute your analog voltage in 8 bit (256 steps each subpixel, so
> 24bit color depth) you get some offset on the transmission
> so you could not use an analog interface in order to transmit data (there
> would only trash arrive)!
> and there is no error correction either.
>
> next thing is that the usb interface is not between the screen and the
> graphics card but between the mainboard and the graphics card
> there is no video transmission at this place!
> it would be more sensible to compare usb to pci-e or agp.

Please stop top-posting; it's difficult to keep the conversation
clear. And see my other reply to you.

--
:wq

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