Re: [libdc] multiple cameras and juju
Capture and control API for IIDC compliant cameras
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From: Samuel A. <sam...@gm...> - 2009-08-10 09:25:25
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Stefan Richter wrote: > The FW323 v5 datasheet claims OHCI 1.1 conformance in the overview but > its register definitions are actually plain OHCI 1.0. > > The FW323 v6 product brief states that the chip can be programmed into > OHCI 1.1 mode or OHCI 1.0 mode by means of the card's serial EEPROM. > Same says the FW643 product brief. > > Many Apple computers contain FW323; Apple happens to program them into > OHCI 1.0 mode for whatever reason. Perhaps for no particular reason at all. > > You can check it in firewire-ohci's initialization message in dmesg. If > these messages are already out of dmesg, you can find them in > /var/log/messages or simply by > # modprobe -r firewire-ohci > # modprobe firewire-ohci > # dmesg | tail The FW323 is loading as OHCI 1.0.. > I'll have you try a simple patch with quirk fix later. Or you could > write one if you like. I'm not sure though whether we should disable > dual buffer for Agere FW643, disable dual buffer for Agere FWxxx, remove > dual buffer mode entirely. Given that Apple, Microsoft, PGR.. and others ? do not even use dual buffer mode by default, I think Linux should follow suit, as it was the case with the old Firewire drivers as well IIRC.. ? But, the driver could automatically white list known working controllers like the TSB82AA2 you have, and we could provide a module parameter so that users may easily enable dual buffers on load, if they feel adventurous.. What do you think? > (a) If FW643 is buggy in dual buffer mode, it's not very unlikely that > the older FWxxx are buggy there too; nobody noticed it yet though > because so many FW323 are EEPROM-programmed to OHCI 1.0 mode. > > (b) Now that FW643 or FWxxx have become known to be buggy in dual buffer > mode, there remains only a _single_ controller which is known to support > dual buffer correctly and is reasonably widespread: The TI TSB82AA2 > 1394b/S800 controller. > > Well, I for one currently have controllers with the following four OHCI > 1.1 controllers and can test them in a PC with 6 GB RAM: > - TI TSB82AA2 -- seems to work, > - TI TSB43AB22(A) -- the buggy one, but I haven't tested it myself in > the 6 GB machine without the quirk fix yet, > - ALi M5271 -- can't test it yet because we need to fix > http://bugzilla.kernel.org/show_bug.cgi?id=10935 first, > - JMicron JMB381 -- seems to work. (Doesn't work very stable BTW. > I have seen its DMA units occasionally getting stuck with the new > drivers and with the old drivers alike.) And I can test the FW643 :) Samuel |