From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754127AbdECSmU (ORCPT ); Wed, 3 May 2017 14:42:20 -0400 Received: from mail-qk0-f172.google.com ([209.85.220.172]:33960 "EHLO mail-qk0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751618AbdECSmM (ORCPT ); Wed, 3 May 2017 14:42:12 -0400 MIME-Version: 1.0 In-Reply-To: <20170408190628.GB16832@bhelgaas-glaptop.roam.corp.google.com> References: <44cada166e42007d27b4c3e3aa0744d7@molgen.mpg.de> <20170408154128.GA16832@bhelgaas-glaptop.roam.corp.google.com> <1491670819.6021.33.camel@infradead.org> <20170408190628.GB16832@bhelgaas-glaptop.roam.corp.google.com> From: Andy Shevchenko Date: Wed, 3 May 2017 21:42:06 +0300 Message-ID: Subject: Re: `pci_apply_final_quirks()` taking half a second To: Bjorn Helgaas Cc: David Woodhouse , Paul Menzel , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 8, 2017 at 10:06 PM, Bjorn Helgaas wrote: > On Sat, Apr 08, 2017 at 07:00:19PM +0200, David Woodhouse wrote: >> ... >> I note it's also reading PCI_CACHE_LINE_SIZE From config space for each >> device in pci_apply_final_quirks(). How long does that take? > > I don't know, but it's pointless on modern PCIe systems where the > Cache Line Size has no effect. It'd be really nice if somebody > cleaned that up and got rid of the read itself and the useless > messages. What I can think of is 10ms delay for PM. The laptop might be one of Intel BayTrails where we have it. But it's just a guess. -- With Best Regards, Andy Shevchenko