Re: [linux-usb-devel] Re: [Spca50x-devs] [BUG] kernel stall in spca50x driver - reopened

[michel Xhaard <mxhaard@xxxxxxxx>]

Le Vendredi 10 Mars 2006 15:31, thomas schorpp a écrit :

> > Thomas,
> > The problem here is very complex that should be:
> > software:
> > 	The usb layer on the kernel API
> > 	The driver specially the spcadecoder
>
> most likely.
>
> > Hardware or firmware:
> > 	The Aiptek DV3500
> > 	The usb Host controller
>
> impossible. unchanged since a year and working fine under winxp.
> and worked under linux fine until at least kernel 2.6.13.
>
> > As in all your report you speak about light or contrast we can raisonably
> > disable the kernel API and the spcadecoder these two parts don't care
> > about light :)
>
> hmm, ok theoretically.
>
> > In the same way we can disable the Usb Host Controller.
> > Now only the Aiptek DV3500 is on the list
> > What about light and the video processor in the DV
> > 	If there are a lot of light the video processor on the DV decrease the
> > times exposure, of course decreasing times exposure will increase the
> > frame rate. As a second effect with a lot of light the jpeg encoder
> > inside the chips find more details in the picture so the picture size
> > increase. With this context we expect a very Hight CPU load
>
> ill check this.
>
> > 	If there are not enought light the video processor increase the times
> > exposure that will of course decrease the frame rate.
> > All this process are know to be Autoexposure, set inside the chips
> > firmware. All spca jpg webcam is set with this feature by default. We did
> > not have acces to this feature, know only by Sunplus and maybe M$
> > developper.
> > I suspect the chips to go out the limit of the Autoexposure and goes to
> > sleep when the interrupt Handler withing the kernel is waiting for data .
>
> this could be traceable with verbose printk logs or debugfs.
> if it is i will try to handle this state somehow if possible.
> but this was surely *no* problem before 2.6.14. it worked just fine.
>
> > I have no
> > solution ATM and cannot produce the same effect as your DV3500 with my
> > old DVII sorry :(
>
> sorry, but ive never seen autoexposure under linux with this device and the
> spca driver. i had to have always adjust brightness manually.
> so this would be out, too.
Can you on a running kernel do the following test:
Dark context choice a room with small light
	run 
	spcaview -d /dev/video0 -f jpg -s 320x240
	after 30s stop spcaview with q
	note the frame rate get in the console.
Bright context maybe outdoor light
	run
	spcaview -d /dev/video0 -f jpg -s 320x240
	after 30s stop spcaview with q
	note the frame rate get in the console.
Is there the same ? can you mail me the result.
> but ill check with windows. would a usbsnoop log help?
I think no, i have a lot from different users, thanks.
> i could send you 
> per postage on data cd. pls tell me which snooper you prefer.
Usually i used Benoit Papillault tools, as i get very accurate result, like my 
Ellisys usb tracker :)
> but many thanks for your comprehensive system analysis and kind
> explanation. i must get behind this. i wont give the device up. it worked
> fine for many months. since i have had many trouble with linux kernel usb
> since using linux, there has been most probably something faulty introduced
> after 2.6.13/14.
>
> Alan Stern was talking on a "bug in the spca driver" on the usb list
> lately, maybe he can comment on this, since i were surely too "limited" to
> get this fixed, cause i didnt went to havard(?) ;)

From kernel people point of vue, there is a big bug in spca5xx.  Spca5xx 
provide uncompressed video, that everyone can used :) Let kernel people 
working as they do a very good job, without us, spca5xx will never works :)
In my opinion this thread is spca5xx specific and can follow the spca50x lists 
at sf, that seem not necessarry to make "noise" on the linux-usb-devel lists. 

Best regards
-- 
Michel Xhaard
http://mxhaard.free.fr


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