[PATCH v9 00/12] use nonblock mmc requests to minimize latency

[Santosh]

+ Balaji,

On Friday 26 August 2011 09:49 PM, Russell King - ARM Linux wrote:
> I'm not sure who's responsible for this, but the nonblocking MMC stuff is
> broken on OMAPs HSMMC:
>
> mmcblk0: error -84 transferring data, sector 149201, nr 64, cmd response 0x900, card status 0xb00
> mmcblk0: retrying using single block read
> ------------[ cut here ]------------
> WARNING: at /home/rmk/git/linux-2.6-rmk/lib/dma-debug.c:811 check_unmap+0x1ac/0x764()
> omap_hsmmc omap_hsmmc.0: DMA-API: device driver tries to free DMA memory it has not allocated [device address=0x0000000080933000] [size=20480 bytes]
> Modules linked in:
> Backtrace:
> [<c0017874>] (dump_backtrace+0x0/0x10c) from [<c02ce8ac>] (dump_stack+0x18/0x1c)
>   r7:c1abfcb8 r6:c0186248 r5:c037de51 r4:0000032b
> [<c02ce894>] (dump_stack+0x0/0x1c) from [<c0039ed4>] (warn_slowpath_common+0x58/0x70)
> [<c0039e7c>] (warn_slowpath_common+0x0/0x70) from [<c0039f90>] (warn_slowpath_fmt+0x38/0x40)
>   r8:c1abfd50 r7:00000000 r6:00005000 r5:00000000 r4:80933000
> [<c0039f58>] (warn_slowpath_fmt+0x0/0x40) from [<c0186248>] (check_unmap+0x1ac/0x764)
>   r3:c0367d55 r2:c037e24d
> [<c018609c>] (check_unmap+0x0/0x764) from [<c0186978>] (debug_dma_unmap_sg+0x100/0x134)
> [<c0186878>] (debug_dma_unmap_sg+0x0/0x134) from [<c0019770>] (dma_unmap_sg+0x24/0x7c)
> [<c001974c>] (dma_unmap_sg+0x0/0x7c) from [<c0207220>] (omap_hsmmc_post_req+0x48/0x54)
> [<c02071d8>] (omap_hsmmc_post_req+0x0/0x54) from [<c01fb644>] (mmc_start_req+0x9c/0x128)
>   r4:c1a76000
> [<c01fb5a8>] (mmc_start_req+0x0/0x128) from [<c02049fc>] (mmc_blk_issue_rw_rq+0x80/0x460)
>   r8:c1ab5c00 r7:00000001 r6:c1ab5824 r5:c1ab5824 r4:c1ab5c00
> [<c020497c>] (mmc_blk_issue_rw_rq+0x0/0x460) from [<c02050a8>] (mmc_blk_issue_rq+0x2cc/0x2fc)
> [<c0204ddc>] (mmc_blk_issue_rq+0x0/0x2fc) from [<c02056c4>] (mmc_queue_thread+0xa0/0x104)
> [<c0205624>] (mmc_queue_thread+0x0/0x104) from [<c0054f8c>] (kthread+0x88/0x90)
> [<c0054f04>] (kthread+0x0/0x90) from [<c003d9a4>] (do_exit+0x0/0x618)
>   r7:00000013 r6:c003d9a4 r5:c0054f04 r4:c1a7bc7c
> ---[ end trace 3314ad56daf5d14f ]---
>
> Luckily thinks continue to work, but clearly releasing DMA mappings which
> drivers don't own is bad news.  Unfortunately, I don't have the bandwidth
> to be able to investigate this at present - well, I could do but then I'd
> have to drop working on the OMAP4 vs generic suspend/resume code and learn
> about something I've no current clue about.
>
Please continue your help on generic suspend.

> Can someone please investigate and fix whatever is broken.
>
Will find somebody to look at this issue.

Regards
Santosh