From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heikki Krogerus Subject: Re: [PATCH] ACPI / LPSS: Ignore 10ms delay for Braswell and Baytrail Date: Thu, 20 Aug 2015 16:04:47 +0300 Message-ID: <20150820130447.GA1337@kuha.fi.intel.com> References: <1440090968-17728-1-git-send-email-srinidhi.kasagar@intel.com> <20150820123805.GG30005@lahna.fi.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mga14.intel.com ([192.55.52.115]:60226 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751283AbbHTNFA (ORCPT ); Thu, 20 Aug 2015 09:05:00 -0400 Content-Disposition: inline In-Reply-To: <20150820123805.GG30005@lahna.fi.intel.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Mika Westerberg Cc: Srinidhi Kasagar , linux-acpi@vger.kernel.org, rafael.j.wysocki@intel.com, Kumar P Mahesh Hi, On Thu, Aug 20, 2015 at 03:38:05PM +0300, Mika Westerberg wrote: > +Heikki > > On Thu, Aug 20, 2015 at 10:46:07PM +0530, Srinidhi Kasagar wrote: > > LPSS devices in Braswell and Baytrail does not need the default > > 10ms d3_delay imposed by PCI specification. Removing this > > unnecessary delay significantly reduces the resume time > > (~200ms on Braswell/Cherrytrail) on these platforms. > > > > Signed-off-by: Srinidhi Kasagar > > Signed-off-by: Kumar P Mahesh > > Have you tested this on Asus T100? The delay was actually needed in > order to restore the context IIRC. We need to make sure the write operation succeeded when restoring the register values. That was the problem we had with T100, which btw. is Baytrail. Instead of using the delay conditionally, why not just read the value back in a loop (with timeout of course) until we see the write succeed? That should speedup the resume like you want, but still guarantee the ctx has really been restored. Thanks, -- heikki