From: gururaja.hebbar@ti•com (Gururaja Hebbar)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v4] ARM: omap: edma: add suspend suspend/resume hooks
Date: Thu, 7 Nov 2013 19:00:11 +0530 [thread overview]
Message-ID: <527B95E3.9060802@ti.com> (raw)
In-Reply-To: <527A7E20.4040107@ti.com>
On Wednesday 06 November 2013 11:06 PM, Joel Fernandes wrote:
> Hi Vaibhav,
>
> On 10/31/2013 05:25 PM, Vaibhav Bedia wrote:
>> Hi Daniel,
>>
>> On Wed, Oct 30, 2013 at 4:21 PM, Daniel Mack <zonque@gmail•com> wrote:
>> [...]
>>> +
>>> +static SIMPLE_DEV_PM_OPS(edma_pm_ops, edma_pm_suspend, edma_pm_resume);
>>> +
>>> static struct platform_driver edma_driver = {
>>> .driver = {
>>> .name = "edma",
>>> + .pm = &edma_pm_ops,
>>> .of_match_table = edma_of_ids,
>>> },
>>
>> A while back we discovered a nasty race condition here that had us move the EDMA
>> PM callbacks to the noirq phase. IIRC the MMC driver was resuming
>> before the EDMA
>> driver had a chance to run and that was leading to a deadlock. I am
>> not sure how to force
>> this scenario but i do remember spending time debugging this on a
>> random codebase.
>> Maybe some else has some better ideas on how to force this race condition...
>
> I think you're talking about the patch at [1] which is not upstream. A quick
> question with my limited knowledge of suspend/resume- How can there be pending
> I/O operations between suspend/resume cycles?
AFAIK, MMC framework started talking to cards immediately after resume.
Due to race condition, EDMA resume callback had not yet completed and
HSMMC driver had initiated a DMA operation. This resulted in Deadlock.
regards
Gururaja
> The sync is done before suspend,
> so I don't understand how one is receiving a response from the card after resume
> before EDMA can resume? I'd imagine that until all devices are resumed, there
> will be no I/O operation issued. Let me know your thoughts.
>
> thanks,
>
> -Joel
>
> [1]
> https://www.gitorious.org/x0148406-public/linux-kernel/commit/b81bf04091986fa3893f31955564594567be3b61
>
next prev parent reply other threads:[~2013-11-07 13:30 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-30 20:21 [PATCH v4] ARM: omap: edma: add suspend suspend/resume hooks Daniel Mack
2013-10-31 22:25 ` Vaibhav Bedia
2013-11-06 17:36 ` Joel Fernandes
2013-11-07 13:30 ` Gururaja Hebbar [this message]
2013-11-07 13:32 ` Daniel Mack
2013-11-07 15:18 ` Nishanth Menon
2013-11-07 15:36 ` Daniel Mack
2013-11-07 15:48 ` Nishanth Menon
2013-11-07 20:42 ` Vaibhav Bedia
2013-11-15 14:39 ` Nishanth Menon
2013-11-17 22:09 ` Daniel Mack
2013-11-07 20:34 ` Vaibhav Bedia
2013-11-07 15:34 ` Nishanth Menon
2013-11-07 16:27 ` Grygorii Strashko
2013-11-07 20:46 ` Vaibhav Bedia
2013-11-07 16:34 ` Joel Fernandes
2013-11-07 16:49 ` Joel Fernandes
2013-11-07 17:37 ` Daniel Mack
2013-11-07 21:39 ` Joel Fernandes
2013-11-08 4:07 ` Gururaja Hebbar
2013-11-08 7:51 ` Daniel Mack
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=527B95E3.9060802@ti.com \
--to=gururaja.hebbar@ti$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox