On 03/28/2015 12:52 AM, NeilBrown wrote:
On Fri, 27 Mar 2015 12:15:15 +0100 Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
Currently those host drivers which have deployed runtime PM, deals with
the runtime PM reference counting entirely by themselves.
Since host drivers don't know when the core will send the next request
through some of the host_ops callbacks, they need to handle runtime PM
get/put between each an every request.
In quite many cases this has some negative effects, since it leads to a
high frequency of scheduled runtime PM suspend operations. That due to
the runtime PM reference count will normally reach zero in-between
every request.
It would be nice to have some numbers about this suspend/resume jitter
of platform device pm due to time between consecutive requests within
burst of requests.
Probably we can tune autosuspend timer of specific platform device to
avoid this.
Implementing the patch in a way that you are suggesting will imply that
the mmc core will always use double buffering request polling scheme and
the existing mechanism of "request burst" definition.
Thanks,
Kostya
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