[Elphel-support] CFAST cards with SATA adapter compatible

[Andrey Filippov]

Sebastian,

Let's hope that the new standard cards support DMA. Standard itself is not
sufficient to find out if these cards will or will not work - as I
described or prior experience, manufacturers of one of the most popular CF
card controllers made it incorrectly respond about the capabilities. So the
only way to find out - try it - if it works - nice, if not - make a small
investigation, maybe it is possible to fix in the driver.

About the UDMA - I have some emails from Axis with their hints, our
investigating of the CF interfacing problems are described in the article
http://www.linuxdevices.com/articles/AT5102023409.html

Andrey


On Sat, Feb 4, 2012 at 12:36 PM, Sebastian Pichelhofer <
sebastian.pichelhofer at gmail.com> wrote:

> Thanks for the details, but CFAST is a completely new standard that
> has little in common with CF cards and also requires totally different
> adapters.
>
> Regarding the UDMA work around hints: Could you help me collect all
> information together we currently have about it (info from axis
> developer, etc.) so I can create a new wiki page describing the task
> and then approach some people.
>
> Regards Sebastian
>
> On Sat, Feb 4, 2012 at 20:28, Andrey Filippov
> <support-list at support.elphel.com> wrote:
> > Sebastian,
> >
> > I just replied Carlos and wrote that the only problem with SATA devices
> was
> > with the old  SSD made actually from the CF cards. Adapter is
> transparent,
> > so if the CF card does not work in the camera directly, it will not work
> > with the adapter.  For slow applications it is possible to disable DMA in
> > the camera (needs adding the lying card to the blacklist and recompiling
> the
> > software).
> >
> > Devices support some of 3 modes:
> >
> > 1) PIO (slow and loads CPU a lot)
> > 2) DMA - fast
> > 3) UDMA - even faster
> > Most CF cards support only 1 and 3 and respond as if they support 2 also
> > ETRAX processor has a bug in implementation of the UDMA, so UDMA is
> > disabled, that means that in the camera we only have 1 and 2. When the
> > camera detects the disk, it loads the device capabilities (1,2,3), and
> > selects the fastest it can support - 2. But here the lie of the CF card
> > controller comes to the light - and the camera fails to communicate with
> the
> > disk. There is a black list of those untruthful cards in the driver, we
> > already added some cards there -
> >
> http://elphel.cvs.sourceforge.net/viewvc/elphel/elphel353-8.0/os/linux-2.6-tag--devboard-R2_10-4/drivers/ide/ide-dma.c?view=markup
> >
> >  Axis engineers said that it is possible to mitigate that bug and gave
> some
> > hints how to do that, but we never worked on it ourselves and it is
> probably
> > not too easy - otherwise Axis people would do it themselves. But if
> anybody
> > with the driver development skills would volunteer - we would definitely
> > love that and support such project.
> >
> > Andrey
> >
> > On Sat, Feb 4, 2012 at 11:53 AM, Sebastian Pichelhofer
> > <sebastian.pichelhofer at gmail.com> wrote:
> >>
> >> Do you think that http://en.wikipedia.org/wiki/CFast#CFast CFast Cards
> >> could work with this adapter:
> >>
> >>
> http://www.amazon.de/exec/obidos/ASIN/b003r4ifmg/geizhals1-21/ref=nosim?m=A3JWKAKR8XB7XF
> >> connected to the Elphel camera over SATA.
> >>
> >> To my understanding the card itself acts like a drive and needs no
> >> controller chip betweencard and camera that could lead to running into
> >> the UDMA issues again. But the card itself might use UDMA... ;)
> >> Any educated guesses?
> >>
> >> Regards Sebastian
> >>
> >> _______________________________________________
> >> Support-list mailing list
> >> Support-list at support.elphel.com
> >>
> http://support.elphel.com/mailman/listinfo/support-list_support.elphel.com
> >
> >
>
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>
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