From: Sujit Reddy Thumma <sthumma@codeaurora.org>
To: Ulf Hansson <ulf.hansson@stericsson.com>
Cc: "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
Chris Ball <cjb@laptop.org>,
Per FORLIN <per.forlin@stericsson.com>,
Lee Jones <lee.jones@linaro.org>
Subject: Re: [PATCH] mmc: core: Prevent too long response times for suspend
Date: Wed, 19 Oct 2011 22:55:07 +0530 [thread overview]
Message-ID: <4E9F07F3.2050103@codeaurora.org> (raw)
In-Reply-To: <4E9BFA84.1040709@stericsson.com>
On 10/17/2011 3:21 PM, Ulf Hansson wrote:
>>
>> Why would there be pending requests while host is suspending? Is the
>> kernel framework not handling sync before going to suspend? However, the
>> mmc_blk_suspend() would be called before the host driver suspends (as all
>> the driver suspend routines are serialized) which means it stops block
>> layer to queue more I/O requests well before the host driver start
>> suspend. Does this sequence break in your case?
>
> I have observed this issue for different cases (one case was logging to
> eMMC). The idea is simply that we would like to be sure that we do not
> wait "forever", no matter if the "upper layers" misbehaved in the
> suspend sequence.
>
Agree. I was just curious to know why would there be a pending requests.
If the issue is seen while logging to eMMC then there may be something
wrong, probably, we may see issue while running mmc_test and initiating
suspend. Your patch looks good to me though.
Reviewed-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
>>
>> Your concern seems to be valid for SDIO case, but again the function
>> driver must be intelligent enough to return -EBUSY as it knows that it
>> had
>> posted a request to MMC.
>>
>
> For SDIO, should we really assume that function driver has implemented a
> suspend function and moreover that it actually always behaves as we expect?
I hope so, but yes, in some cases that may be broken. I agree with you.
>
> Br
> Ulf Hansson
--
Thanks & Regards,
Sujit Reddy Thumma
next prev parent reply other threads:[~2011-10-19 17:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-13 14:03 [PATCH] mmc: core: Prevent too long response times for suspend Ulf Hansson
2011-10-15 6:47 ` Sujit Reddy Thumma
2011-10-17 9:51 ` Ulf Hansson
2011-10-19 17:25 ` Sujit Reddy Thumma [this message]
2011-10-19 22:09 ` Linus Walleij
2011-10-21 4:25 ` Chris Ball
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