From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Stern Subject: Re: [PATCH] sdhci: wakeup from runtime PM Date: Fri, 8 Apr 2016 11:19:16 -0400 (EDT) Message-ID: References: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: Received: from iolanthe.rowland.org ([192.131.102.54]:36966 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1758533AbcDHPTS (ORCPT ); Fri, 8 Apr 2016 11:19:18 -0400 In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Ulf Hansson Cc: Ludovic Desroches , Nicolas Ferre , Adrian Hunter , "linux-pm@vger.kernel.org" , linux-mmc 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