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Connecting a SATA 3 HDD to the SATA 2 peripheral module of an OMAP-L138?

Kevin Bleibaum
Prodigy 120 points
Other Parts Discussed in Thread: OMAP-L138

All,

We are still looking for a solution to using a SATA 3 compliant HDD with the SATA 2 peripheral module found in several of TI's processors. I believe all of their devices are only supporting a SATA 2 (or GEN2) peripheral module, which has a max. data rate of 3 Gb/s. What we need is a device that will support SATA 3 (GEN3) drives which have a max. data rate of 6 Gb/s. The data rate itself is not the concern. The concern is that hard drive market seems to be migrating toward drives with SATA 3 interfaces only (some of which are backwardly compatible and can negotiate and operate at SATA 2 data rates.) But connecting a SATA 3 hard drive to our current device, the OMAP-L138, causes it to fail by refusing to completely negotiate the physical link.

We're aware of the workarounds provided in the Errata " OMAP-L138 C6-Integra™ DSP+ARM® Low-Power Applications Processor Silicon Revisions 2.1, 2.0, 1.1 and 1.0 Silicon Errata" and they are not really solutions for us. We want to be able to take a SATA 3 (GEN3) hard drive, connect it to some TI device, and have it operate at (least at) SATA 2 speeds. We're willing to change processors if that's what is required.
 
Perhaps there is a way we can use some "SATA 3 <-> SATA 2" bridge or other hardware, to connect the SATA2 peripheral module (e.g. Megamodule SATA in OMAP-L138) to a SATA3 hard disk (especially SSDs, which seem to be migrating to SATA3-only very quickly)? We exercised an external RAID enclosure (supporting two 2.5" HDDs) thinking that the additional circuitry provided to support the port multiplier would improve SATA 3 HDD connectivity, to no avail.
 
Maybe there is way to hang a dedicated SATA 3 PHY part off the TI processor, on the system or host bus, and achieve SATA 2 transfer rates (3 Gb/s)? Thereby bypassing the peripheral module entirely? Transfering data using EDMA3?
 
Doesn't seem like we'd be the only ones concerned about this. SATA 3 is becoming more and more popular. Having a SATA 2 interface that refuses to connect to a SATA 3 drive is a concern. TI has suggested that this issue is not currently on their roadmap for future devices.

Any suggestions greatly appreciated,
Kevin

  • 0
    TI__Guru* 83745 points

    Kevin

    This question got routed to me, and I believe we have discussed this a bit in another post with you. I have pinged my counterparts in the DM814x team to see if any other software work around or SATA bridge has worked. AFAIK, not aware of any workarounds beyond what is provided in the errata.

    I do hear you that with SATAIII drives becoming more prominent, this is going to be difficult to deal with.

    Did you manage to contact your local TI sales, and did they manage to recommend any other TI device that might be a better fit for your usecase and end application?

    Regards

    Mukul

  • 0 in reply to Mukul Bhatnagar
    Prodigy 120 points

    Mukul,

    Thanks. Yes, this is the same issue we discussed before. I did contact my local TI rep and he talked with the production guys. Response was that there was no SATA III interface in development on ANY processor, or on a roadmap. His suggestion was to put this distress call back on the boards. So here we are.

    We did try a single SATAIII drive in an external two-bay enclosure. The enclosure has sufficient backplane electronics to support RAID0 (via a Port Multiplier, I think). The thinking here was that the additional electronics would be sufficient to convince the OMAP-L138's SATAII peripheral module to connect to a SATAIII. It did not.

    We're willing to modify our hardware design if necessary, including adding a dedicated SATAIII peripheral chip, provided we can DMA from the UPP port of the OMAP-L138 at a minimum rate of 1 Gbps.

    Regards,

    Kevin