Re: [PATCH] sdhci: wakeup from runtime PM

Alan Stern
2016-04-08T15:19:16Z

On Fri, 8 Apr 2016, Ulf Hansson wrote:

> From power consumption point if view we already discussed this
> particular case in an earlier thread, but let me elaborate what I
> think one more time:
>
> Now, this is relevant for removable cards lacking GPIO card detect, as
> for other cases and non-removable cards I think we are in agreement
> that their is no issue from power consumption point of view, right!?
>
> 1. The current solution:
> - Use MMC_CAP_NEEDS_POLL which makes the mmc core to re-schedule a
> work once every second to poll for a card (Why is it one second? Could
> we perhaps have that configurable?).

The block layer handles media polling for removable block devices, and
it is configurable. For example, /sys/block/sr0/events_poll_msecs can
be set to control how often the system polls for a disc in my DVD
drive.

Does MMC do its own polling separate from the block layer? If so, why?

Alan Stern