From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konstantin Dorfman Subject: Re: [PATCH] mmc: core: Enable runtime PM management of host devices Date: Sun, 29 Mar 2015 13:53:53 +0300 Message-ID: <5517D9C1.5080302@codeaurora.org> References: <1427454915-12893-1-git-send-email-ulf.hansson@linaro.org> <20150328085242.5e1e1acc@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:55536 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751750AbbC2Kx6 (ORCPT ); Sun, 29 Mar 2015 06:53:58 -0400 In-Reply-To: <20150328085242.5e1e1acc@notabene.brown> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: NeilBrown , Ulf Hansson Cc: linux-mmc@vger.kernel.org, Adrian Hunter On 03/28/2015 12:52 AM, NeilBrown wrote: > On Fri, 27 Mar 2015 12:15:15 +0100 Ulf Hansson 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 -- Qualcomm Israel, on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project