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Message-ID: <CAJ0pr18vZkQop29_ReNU6rP+nMORaz2+FOa4P0rLTfihfDd6=w@mail.gmail.com>
Date: Sun, 28 Aug 2011 12:50:54 +0200
From: Per Forlin <per.forlin@...aro.org>
To: Santosh <santosh.shilimkar@...com>
Cc: Russell King - ARM Linux <linux@....linux.org.uk>,
linux-omap@...r.kernel.org,
Nicolas Pitre <nicolas.pitre@...aro.org>,
Chris Ball <cjb@...top.org>, linaro-dev@...ts.linaro.org,
Arnd Bergmann <arnd@...db.de>,
Linus Walleij <linus.walleij@...aro.org>,
linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
Kyungmin Park <kyungmin.park@...sung.com>,
Sourav Poddar <sourav.poddar@...com>,
linux-arm-kernel@...ts.infradead.org,
Balaji T Krishnamoorthy <balajitk@...com>
Subject: Re: [PATCH v9 00/12] use nonblock mmc requests to minimize latency
On 26 August 2011 18:28, Santosh <santosh.shilimkar@...com> wrote:
> + 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.
>
I had a look at this and my guess is that the same mapped DMA memory
is unmapped twice. First the memory is unmapped in
omap_hsmmc_dma_cleanup() due to the mmc error, then later in
omap_hsmmc_post_req(). Here is a patch to resolve that. I haven't had
the chance to test it yet though.
---
drivers/mmc/host/omap_hsmmc.c | 7 +++++--
1 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index 21e4a79..7f40767 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -1011,6 +1011,7 @@ static void omap_hsmmc_dma_cleanup(struct
omap_hsmmc_host *host, int errno)
host->data->sg_len,
omap_hsmmc_get_dma_dir(host, host->data));
omap_free_dma(dma_ch);
+ data->host_cookie = 0;
}
host->data = NULL;
}
@@ -1576,8 +1577,10 @@ static void omap_hsmmc_post_req(struct mmc_host
*mmc, struct mmc_request *mrq,
struct mmc_data *data = mrq->data;
if (host->use_dma) {
- dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
- omap_hsmmc_get_dma_dir(host, data));
+ if (data->host_cookie)
+ dma_unmap_sg(mmc_dev(host->mmc), data->sg,
+ data->sg_len,
+ omap_hsmmc_get_dma_dir(host, data));
data->host_cookie = 0;
I also checked the mmci code for this same issue and mmci doesn't have
the same bug.
MMCI works fine in 3.1-rc2 even though the code is "wrong". I propose
this change.
@@ -529,7 +529,7 @@ static void mmci_post_request(struct mmc_host
*mmc, struct mmc_request *mrq,
if (chan) {
if (err)
dmaengine_terminate_all(chan);
- if (err || data->host_cookie)
+ if (data->host_cookie)
I'll post these patches as soon as I have managed to test them or
sooner if I get a tested-by.
Regards,
Per
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