From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ulf Hansson Subject: Re: [PATCH] sdhci: wakeup from runtime PM Date: Fri, 8 Apr 2016 22:51:51 +0200 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from mail-wm0-f44.google.com ([74.125.82.44]:34958 "EHLO mail-wm0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751890AbcDHUvx (ORCPT ); Fri, 8 Apr 2016 16:51:53 -0400 Received: by mail-wm0-f44.google.com with SMTP id 191so29264862wmq.0 for ; Fri, 08 Apr 2016 13:51:52 -0700 (PDT) In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Alan Stern Cc: Ludovic Desroches , Nicolas Ferre , Adrian Hunter , "linux-pm@vger.kernel.org" , linux-mmc On 8 April 2016 at 17:19, Alan Stern wrote: > 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? Good question. Probably because of legacy or perhaps to deal with corner cases. When I get some spare bandwidth I will check to see if it makes sense to convert MMC polling to the block layer polling. Kind regards Uffe