From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752237AbcBVJ4k (ORCPT ); Mon, 22 Feb 2016 04:56:40 -0500 Received: from comal.ext.ti.com ([198.47.26.152]:35752 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751198AbcBVJ4i (ORCPT ); Mon, 22 Feb 2016 04:56:38 -0500 Subject: Re: [PATCH v3 3/3] pci: dra7xx: use pdata callbacks to perform reset To: Paul Walmsley References: <1452780672-14339-1-git-send-email-kishon@ti.com> <1452780672-14339-4-git-send-email-kishon@ti.com> <20160127173104.GQ19432@atomide.com> <56A90971.4020409@ti.com> <20160127185649.GV19432@atomide.com> <56A94FB7.6020903@ti.com> <20160128183156.GH19432@atomide.com> <56B087AD.4000505@ti.com> <56B900E9.9040306@ti.com> <56BA2495.9020407@ti.com> <56BA958A.1020503@ti.com> <56BACCDB.2070507@ti.com> <56BD8091.4090007@ti.com> <56BE1454.3030002@ti.com> <56C5D377.50901@ti.com> <56CAA82D.6000507@ti.com> CC: Sekhar Nori , Suman Anna , , Tony Lindgren , Bjorn Helgaas , , Russell King , , , From: Kishon Vijay Abraham I Message-ID: <56CADB23.8020202@ti.com> Date: Mon, 22 Feb 2016 15:25:47 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Paul, On Monday 22 February 2016 12:01 PM, Paul Walmsley wrote: > Kishon, > > On Mon, 22 Feb 2016, Kishon Vijay Abraham I wrote: > >> Sekhar, >> >> On Thursday 18 February 2016 07:51 PM, Sekhar Nori wrote: >>> On Friday 12 February 2016 10:50 PM, Suman Anna wrote: >>>> Sekhar, >>>> Will you be following up with above suggestion since Kishon is gonna be out? >>> >>> Alright, noticed this action for me :) Went through the thread, and >>> looks like this is what we want to see? >>> >>> Thanks, >>> Sekhar >>> >>> ---8<--- >>> From e3ba368f2235e1bf38a22ba8ea4e5c12aaafda19 Mon Sep 17 00:00:00 2001 >>> Message-Id: >>> From: Sekhar Nori >>> Date: Thu, 18 Feb 2016 16:49:56 +0530 >>> Subject: [PATCH 1/1] ARM: DRA7: hwmod: Add custom reset handler for PCIeSS >>> >>> Add a custom reset handler for DRA7x PCIeSS. This >>> handler is required to deassert PCIe hardreset lines >>> after they have been asserted. >>> >>> This enables the PCIe driver to access registers after >>> PCIeSS has been runtime enabled without having to >>> deassert hardreset lines itself. >>> >>> With this patch applied, used lspci to make sure >>> connected PCIe device enumerates on DRA74x and DRA72x >>> EVMs. >>> >>> Signed-off-by: Sekhar Nori >>> --- >>> Applies to tag for-v4.6/omap-hwmod-a of Paul W's tree. >>> >>> arch/arm/mach-omap2/omap_hwmod_7xx_data.c | 23 +++++++++++++++++++++++ >>> 1 file changed, 23 insertions(+) >>> >>> diff --git a/arch/arm/mach-omap2/omap_hwmod_7xx_data.c b/arch/arm/mach-omap2/omap_hwmod_7xx_data.c >>> index b61355e2a771..252b74633e31 100644 >>> --- a/arch/arm/mach-omap2/omap_hwmod_7xx_data.c >>> +++ b/arch/arm/mach-omap2/omap_hwmod_7xx_data.c >>> @@ -1526,8 +1526,31 @@ static struct omap_hwmod dra7xx_ocp2scp3_hwmod = { >>> * >>> */ >>> >>> +/* >>> + * As noted in documentation for _reset() in omap_hwmod.c, the stock reset >>> + * functionality of OMAP HWMOD layer does not deassert the hardreset lines >>> + * associated with an IP automatically leaving the driver to handle that >>> + * by itself. This does not work for PCIeSS which needs the reset lines >>> + * deasserted for the driver to start accessing registers. >>> + * >>> + * We use a PCIeSS HWMOD class specific reset handler to deassert the hardreset >>> + * lines after asserting them. >>> + */ >>> +static int dra7xx_pciess_reset(struct omap_hwmod *oh) >>> +{ >>> + int i; >>> + >>> + for (i = 0; i < oh->rst_lines_cnt; i++) { >>> + omap_hwmod_assert_hardreset(oh, oh->rst_lines[i].name); >>> + omap_hwmod_deassert_hardreset(oh, oh->rst_lines[i].name); >>> + } >>> + >>> + return 0; >>> +} >>> + >>> static struct omap_hwmod_class dra7xx_pciess_hwmod_class = { >>> .name = "pcie", >>> + .reset = dra7xx_pciess_reset, >>> }; >> >> Thanks for the patch. > > Could you please test the bind/unbind functionality just to make sure it > works? The pci-dra7xx driver neither expose the bind/unbind sysfs entry nor can be built as module. However I hacked the pci-dra7xx driver to be built as module [and reverted Commit 5de85b9d57ab ("PM / runtime: Re-init runtime PM states at probe error and driver unbind")] and I don't see an abort when the PCI registers are accessed after rmmod/modprobe cycle (that was the issue that Sekhar's patch tried to solve). However PCI as such doesn't work after rmmod/modprobe cycle [1], but this is a different issue most likely in PCIe core and has to debugged. In summary, there are other issues in PCI across rmmod/modprobe cycle but the reset of pci-dra7xx happens fine with this patch. Thanks Kishon [1] -> http://pastebin.ubuntu.com/15169387/