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SSD SATA Support in OMAPl138?

vijayabharathi chelladurai
Intellectual 955 points
Other Parts Discussed in Thread: OMAPL138

Hi

 

We are using SSD SATA in our application instead of traditional SATA HDD. We know OMAP l138 supports traditional SATA HDD. What about OMAPl138 support for SSD?

We planned to use below SSD drive

http://www.crucial.com/store/partspecs.aspx?IMODULE=CT256M4SSD2

Spec says its 6Gbps device, but 3Gbps backward compatible. So will OMAPl138 support the above SSD drive?

KIndly advise us

 

Regards

Vijayabharathi C

 

 

 

 

  • 0
    TI__Expert 5475 points

    Hi,

    The OMAPL138 supports GEN1 (1.5Gbits/Sec) and GEN2 (3.0Gbits/Sec) speed raw line speed. It does not support GEN3 (6Gbits/Sec) speed. The OMAPL138 supports AHCI Host controller and has no support for legacy operation.

    Having said that, in theory whether the target is a Hard Disk Drive or Solid State Drive or CD like device, and has the support for GEN3 capability, it has to be downward compatible. We have seen issues with some GEN3 devices. So long as the SSD is compliant to the SATA spec and is downward compatible with the lower speeds, then it should be able to establish link and communicate with the OMAPL138 AHCI Host controller. In other words, it is really up to the SSD since it is the one requesting the line speed for link establishment.

    Best regards, Zegeye

  • 0 in reply to Zegeye Alemu
    Intellectual 955 points

    Hi

    I tried to connect the SSD drive and verify its working in our custom board. Iam getting inconsistent results. It gets connected sometimes,sometimes not. Sometimes Linux Kernel shows the connected SSD drives. Sometimes kernel shows "SATA link down".What is more puzzling for me is, it shows it operates at 1.5Gbps, but current device operates only at 6 Gbps or 3Gbps.I have even limited the speed of SATA controller inside OMAP to 3Gbps, but still inconsitent.

    Seagate Barracuda SATA drive is working consitently with current custom board

    Kindly advise me whether i have to change any setting corresponding to SSD drives in OMAP SATA controller

    Regards

    Vijayabharathi C

  • 0 in reply to vijayabharathi chelladurai
    TI__Expert 5475 points

    Hi,

    It is possible that the GEN3 signaling confiusing the SATA Subsystem. We are currently looking into this issue and most likely will come up with an advisory stating that our device could have an issue with link establishment when using GEN3 capable device.

    That said, if you use a GEN2 capable SSD Drive, I expect to see no problem. Note that this is true for GEN3 HDDs too.

    Best regards, Zegeye

  • 0 in reply to Zegeye Alemu
    Intellectual 275 points

    Hi Zegeye,

    Do you have any update on this issue?

    Putting a crucial m4 on my system with kernel 2.6.33-rc4 I got really poor write performance (10MB/s).

    To compare on 1TB classical hard disk I got 16MB/s

    Thanks for any feedback.

  • 0 in reply to ldufrechou
    Intellectual 275 points

    Ok, reading http://processors.wiki.ti.com/index.php/TI_SATA_FAQ.

    I used O_DIRECT which boosted dramatically teh performance of the SSD. (>44MB/s)

    No more issue now.