Re: [RFC PATCH] mmc: Enable wakeup_sources for mmc core

From: Zoran Markovic
Date: Thu Aug 01 2013 - 03:42:39 EST

I got confirmation from Broadcom that all cell phone reference designs
have card insert/removal configured as a wakeup IRQ. Unless our
customers change that - which I doubt - this results in a considerable
number of products implementing this feature.

Please let me know how you wish to proceed.


On 26 June 2013 13:57, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
> On 24 June 2013 21:58, Zoran Markovic <zoran.markovic@xxxxxxxxxx> wrote:
>>>> This patch is ported from the Android common tree, so you've probably
>>>> been using it.
>>> We removed more or less all Android code in the mmc subsystem, since
>>> it just didn't work. :-)
>>> The "deferred resume" was very useful though, so after some rework we
>>> kept it and could then improve the system resume time significantly.
>> For what it's worth, I fixed one bug I noticed in the Android kernel:
>> if a system has a non-removable MMC device, a suspend/resume cycle on
>> this device would hold a wake lock forever. This was a visible issue
>> on the panda board I am using.
>> If there are doubts on whether or not the system should stay awake
>> during a MMC mount, we have the option to make the calls to
>> wakeup_source_register/unregister configurable. Skipping these calls
>> would leave the .ws field NULL, in which case
>> __pm_stay_awake/__pm_relax/__pm_wakeup_event would do nothing.
> Even if we make this feature configurable, I can't see any host driver
> that would benefit from it as of today. The reason is simply that host
> drivers do not configure it's card detect irq as a wakeup irq. Myself
> is also having quite hard to see the benefit of doing that, but I
> don't know all the use cases.
> Let's see if we can get someone else to provide input...
>> Thoughts?
>> - Zoran
> Kind regards
> Ulf Hansson
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