Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752099AbdHASIg (ORCPT ); Tue, 1 Aug 2017 14:08:36 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:42590 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751910AbdHASIe (ORCPT ); Tue, 1 Aug 2017 14:08:34 -0400 Subject: Re: [PATCH v3 2/2] memory: ti-emif-sram: introduce relocatable suspend/resume handlers From: Santosh Shilimkar To: Arnd Bergmann , Olof Johansson , Olof Johansson Cc: Dave Gerlach , Russell King , Rob Herring , Tony Lindgren , Santosh Shilimkar , linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Keerthy J , Johan Hovold , Greg Kroah-Hartman References: <20170724212454.27574-1-d-gerlach@ti.com> <20170724212454.27574-3-d-gerlach@ti.com> <9b856bf5-f404-5cfc-6f1e-5ae527c6e0b1@oracle.com> Organization: Oracle Corporation Message-ID: Date: Tue, 1 Aug 2017 11:08:19 -0700 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <9b856bf5-f404-5cfc-6f1e-5ae527c6e0b1@oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3121 Lines: 68 On 7/26/2017 9:54 AM, Santosh Shilimkar wrote: > > On 7/24/2017 2:24 PM, Dave Gerlach wrote: >> Certain SoCs like Texas Instruments AM335x and AM437x require parts >> of the EMIF PM code to run late in the suspend sequence from SRAM, >> such as saving and restoring the EMIF context and placing the memory >> into self-refresh. >> >> One requirement for these SoCs to suspend and enter its lowest power >> mode, called DeepSleep0, is that the PER power domain must be shut off. >> Because the EMIF (DDR Controller) resides within this power domain, it >> will lose context during a suspend operation, so we must save it so we >> can restore once we resume. However, we cannot execute this code from >> external memory, as it is not available at this point, so the code must >> be executed late in the suspend path from SRAM. >> >> This patch introduces a ti-emif-sram driver that includes several >> functions written in ARM ASM that are relocatable so the PM SRAM >> code can use them. It also allocates a region of writable SRAM to >> be used by the code running in the executable region of SRAM to save >> and restore the EMIF context. It can export a table containing the >> absolute addresses of the available PM functions so that other SRAM >> code can branch to them. This code is required for suspend/resume on >> AM335x and AM437x to work. >> >> In addition to this, to be able to share data structures between C and >> the ti-emif-sram-pm assembly code, we can automatically generate all of >> the C struct member offsets and sizes as macros by making use of the ARM >> asm-offsets file. In the same header that we define our data structures >> in we also define all the macros in an inline function and by adding a >> call to this in the asm_offsets file all macros are properly generated >> and available to the assembly code without cluttering up the asm-offsets >> file. >> >> Signed-off-by: Dave Gerlach >> --- [...] >> >> arch/arm/kernel/asm-offsets.c | 4 + >> drivers/memory/Kconfig | 10 ++ >> drivers/memory/Makefile | 4 + >> drivers/memory/emif.h | 17 ++ >> drivers/memory/ti-emif-pm.c | 339 >> +++++++++++++++++++++++++++++++++++++++ >> drivers/memory/ti-emif-sram-pm.S | 334 >> ++++++++++++++++++++++++++++++++++++++ >> include/linux/ti-emif-sram.h | 147 +++++++++++++++++ >> 7 files changed, 855 insertions(+) >> create mode 100644 drivers/memory/ti-emif-pm.c >> create mode 100644 drivers/memory/ti-emif-sram-pm.S >> create mode 100644 include/linux/ti-emif-sram.h >> > I will need RMKs blessing since he reviewed the ASM code. > > Also need work out how to line this up. Typically I use to get > driver/memory patches via Greg's driver-core but this is more > PM code than memory driver and very SOC specific. > > Hi Arnd/Olof, > Will you be ok to pull this via arm-soc ? There is also follow > up platform PM code and DTS series which will make use of this. > Looks like I missed to copy Olof. Let me know guys if you are ok to pull this into your driver-soc given the dependencies. Regards Santosh