SAMA5D27-WLSOM1 + Linux4SAM: resume from Backup Self-Refresh mode

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SAMA5D27-WLSOM1 + Linux4SAM: resume from Backup Self-Refresh mode

Wed Oct 16, 2019 11:41 am

A question particularly for the Microchip engineers on this forum - is Linux4SAM "resume from mem-sleep" proven on the WLSOM1 (SAMA5D27 with LPDDR2) using Backup Self-Refresh mode?
I see that Claudiu Beznea made a commit to AT91Bootstrap 9 days ago "Add BSR support for LPDDR2 memories with SAMA5D2", but there hasn't been a commit to Linux4SAM in this area for many months. In my current debug setup (a custom PCB using the ATSAMA5D27C-LD2G LPDDR2 SIP), it appears that the pointers stored in SECURAM on the SAMA5 are being maintained during mem-sleep, but data in LPDDR2 are being lost or corrupted, which suggests to me that Linux4SAM is not correctly configuring the MPDDRC (Multiport DDR-SDRAM Controller) registers before going to sleep. I'd like to know whether this feature has been proved to work on (say) a WLSOM1-EK board, or is a Microchip work-in-progress, before spending time looking at possible hardware (power-supply-related) causes on our board.

Thank you,
Mike H.
ASH Wireless

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