Proposal posted: SAS-3 addition of POWER DISABLE

T. C. McNally tc.mcnally at newisys.com
Fri Aug 17 05:51:16 PDT 2012


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1208170_f.htm">HTML-formatted message</a>

All,
Is the pin choice for POWER DISABLE negotiable?  I would ask for this
function to be on P1.
Thanks,
T. C. Mc Nally
System Engineer
719-884-8733
On Thu, Aug 16, 2012 at 4:16 PM, Besmer, Brad <Brad.Besmer at lsi.com> wrote:
> Alvin,****
>
> ** **
>
> Few discussion items:****
>
> ** **
>
> 1 - There is no associated support in SPL-2 for this (ie. Identify /
> Discover). How does the attached entity know if the target device supports
> this behavior or not?****
>
> ** **
>
> 2 –What happens to the link-state when the POWER DISABLE signal is
> asserted?****
>
> ** **
>
> 3 – How does attached device know if the device has been hot-swapped with
> a different device?****
>
> ** **
>
> 4 – What other system-level impacts does this have?****
>
> ** **
>
> Brad****
>
> ** **
>
> *From:* owner-t10 at t10.org [mailto:owner-t10 at t10.org] *On Behalf Of *Felton,
> Mickey
> *Sent:* Thursday, August 16, 2012 3:39 PM
> *To:* Alvin Cox; T10 Reflector
> *Subject:* RE: Proposal posted: SAS-3 addition of POWER DISABLE****
>
> ** **
>
> Alvin- ****
>
> EMC agrees with the principal behind this proposal, but a few questions:**
> **
>
> ** **
>
> How long after stable 12V / 5V is the circuitry ready? Could it be
> asserted while power is ramping up? ****
>
> Does the input signal on the drive have any special edge or level
> requirements?****
>
> ** **
>
> Thanks!****
>
> -Mick****
>
> ** **
>
> ** **
>
> ** **
>
> *From:* owner-t10 at t10.org [mailto:owner-t10 at t10.org <owner-t10 at t10.org>]
*On
> Behalf Of *Alvin Cox
> *Sent:* Thursday, August 16, 2012 12:33 PM
> *To:* T10 Reflector
> *Subject:* Proposal posted: SAS-3 addition of POWER DISABLE****
>
> ** **
>
> This proposal changes the functions of P1, P2, and P3 from 3.3V. The
> signal assignment of these pins have been changed by other standards that
> intermate with SAS connectors. Please review this proposal. The proposal
> may be downloaded at:
>   http://www.t10.org/cgi-bin/ac.pl?t=d&f=12-363r0.pdf
>
> This proposal was introduced on the 8/16/12 SAS PHY call and will be the
> first discussion item on the 8/23/12 SAS PHY call.****
>
> *Abstract *****
>
> This proposal documents the changes associated with the addition of POWER
> DISABLE to SAS-3. This function provides a means for the SAS target device
> with a SAS Drive plug connector or SAS MultiLink Drive plug connector to
> remove D.C. power (+5V and +12V) from the drive circuitry when the power
> disable signal is driven high by the system. The POWER DISABLE signal is
> specified on P3. If POWER DISABLE is not supported, P3 shall be not
> connected. P1 and P2 are shorted together to provide the same connection as
> on SAS drives compliant with versions of the SAS standard previous to
> SAS-3, and to be consistent with the recommended implementation specified
> by SATA since P1 and P2 have been retired and P3 may implement DEVSLP. The
> functional polarity of POWER DISABLE is consistent with DEVSLP if the
> DEVSLP function is enabled.****
>
>  Extensive research was done prior to drafting this proposal with respect
> to system implementation on P1, P2, and P3. No instances were found where
> systems provided 3.3V power to these pins. Maintaining the connection of P1
> to P2 provided the widest support of legacy implementations that used the
> pins for functionality not specified by the SAS standard.****
>
>
>
> --
> Alvin Cox
> Seagate Technology, LLC
> Cell 405-206-4809
> Office 405-392-3738
> E-Mail  alvin.cox at seagate.com ****
>
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