[Elphel-support] CFAST cards with SATA adapter compatible

[Sebastian Pichelhofer]

On Sat, Feb 4, 2012 at 21:24, Andrey Filippov
<support-list at support.elphel.com> wrote:
> 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.

Will do, I should be able to get both card and adapter for less than
100€ and will report back with results.

>
> 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

If you could dig them out that would be great.

Regards Sebastian

>
> 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
>> >>
>> >> _______________________________________________
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>> >> Support-list at support.elphel.com
>> >>
>> >> http://support.elphel.com/mailman/listinfo/support-list_support.elphel.com
>> >
>> >
>>
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>
>