Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753451AbdHKPo5 (ORCPT ); Fri, 11 Aug 2017 11:44:57 -0400 Received: from lelnx193.ext.ti.com ([198.47.27.77]:49266 "EHLO lelnx193.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752901AbdHKPoz (ORCPT ); Fri, 11 Aug 2017 11:44:55 -0400 Subject: Re: [PATCH v3 2/2] memory: ti-emif-sram: introduce relocatable suspend/resume handlers To: Santosh Shilimkar , Arnd Bergmann , Olof Johansson References: <20170724212454.27574-1-d-gerlach@ti.com> <20170724212454.27574-3-d-gerlach@ti.com> <9b856bf5-f404-5cfc-6f1e-5ae527c6e0b1@oracle.com> CC: Russell King , Rob Herring , Tony Lindgren , Santosh Shilimkar , , , , , Keerthy J , Johan Hovold , Greg Kroah-Hartman From: Dave Gerlach Message-ID: <42672b14-8242-0a5b-f343-8e0fa38ffaaf@ti.com> Date: Fri, 11 Aug 2017 10:42:34 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [128.247.59.203] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3390 Lines: 78 Russell/Johan, On 08/01/2017 01:08 PM, Santosh Shilimkar wrote: > 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. Any additional comments here? I believe I have addressed everything from v2 so hopefully this is acceptable now. Regards, Dave > > Regards > Santosh >