From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751408AbaK1XKu (ORCPT ); Fri, 28 Nov 2014 18:10:50 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:32897 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751259AbaK1XKs (ORCPT ); Fri, 28 Nov 2014 18:10:48 -0500 Message-ID: <547900D2.6050404@roeck-us.net> Date: Fri, 28 Nov 2014 15:10:10 -0800 From: Guenter Roeck User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Stefan Agner , Arnd Bergmann CC: linux-arm-kernel@lists.infradead.org, shawn.guo@linaro.org, kernel@pengutronix.de, linux-kernel@vger.kernel.org, fkan@apm.com Subject: Re: [PATCH 2/2] ARM: imx: src: support vf610 system reset controller References: <1417193015-6033-1-git-send-email-stefan@agner.ch> <2716009.DOfHfaSPkY@wuerfel> <6341b31998ff843d236bc2a3e34537b0@agner.ch> <18555848.LVhqYu0kXL@wuerfel> In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CTCH-PVer: 0000001 X-CTCH-Spam: Unknown X-CTCH-VOD: Unknown X-CTCH-Flags: 0 X-CTCH-RefID: str=0001.0A020209.547900D8.0056,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-Score: 0.001 X-CTCH-ScoreCust: 0.000 X-CTCH-Rules: C_4847, X-CTCH-SenderID: linux@roeck-us.net X-CTCH-SenderID-Flags: 0 X-CTCH-SenderID-TotalMessages: 2 X-CTCH-SenderID-TotalSpam: 0 X-CTCH-SenderID-TotalSuspected: 0 X-CTCH-SenderID-TotalConfirmed: 0 X-CTCH-SenderID-TotalBulk: 0 X-CTCH-SenderID-TotalVirus: 0 X-CTCH-SenderID-TotalRecipients: 0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: mailgid no entry from get_relayhosts_entry X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/28/2014 03:00 PM, Stefan Agner wrote: > On 2014-11-28 23:22, Arnd Bergmann wrote: >> On Friday 28 November 2014 23:09:09 Stefan Agner wrote: >>> On 2014-11-28 22:24, Arnd Bergmann wrote: >>>> On Friday 28 November 2014 22:02:01 Stefan Agner wrote: >>>> >>>>>> If the SRC is also capable of resetting individual blocks instead of just >>>>>> the entire machine, it would be a reset driver in drivers/reset instead. >>>>> >>>>> Beside the system reset, there is only a mask functionality for the >>>>> watchdogs (there are two watchdogs, one for Cortex-A5 and one for the >>>>> M4). This makes the SRC module in the Vybrid a bit different then what >>>>> is available on other i.MX SoC's... >>>> >>>> If you already have the watchdog registers in there and want to have >>>> a watchdog driver too, the easiest way would be to register the reboot >>>> handler from the watchdog driver. >>> >>> Hm, not sure we speak about the same here. The SRC module has two >>> (multi-)bit fields to mask the watchdog reset event for each watchdog. >>> Beside that, there are two full watchdog register maps, which are in >>> different areas. There is already a driver for this watchdogs. I'm not >>> sure what the idea behind this is exactly, I guess it would easily allow >>> to (temporary) mask the other CPU's watchdog. However, I don't think we >>> need that functionality, so I don't care about that right now. >> >> Ok, I see, thanks for the clarification! >> >>> There is also a restart handler in the watchdog driver, but I prefer to >>> use the reset capabilities of the SRC since it has immediate effect. >>> >>> Lets get to the big picture again: I could register the whole SRC >>> register map as a syscon device and then access the registers from my >>> suspend/resume implementation later on. And similar in the restart >>> driver, I would use syscon_regmap_lookup_by_compatible to check if it >>> contains the vf610-src compatible string and register the restart >>> driver/handler if available. >> >> Correct, and also in the watchdog driver, I guess. >> >> Instead of syscon_regmap_lookup_by_compatible, please use >> syscon_regmap_lookup_by_phandle and put the link to the syscon >> device into the device accessing it. >> >> Also, see if you can use or extend drivers/power/reset/syscon-reboot.c >> for your use case. > > Nice, this allows to do the reset with almost no code. The only thing > which might be a problem is the priority: I used 192 since 128 is > already used by the watchdog driver. Maybe we can change that > syscon-reboot is a bit above watchdogs by default, or maybe even a dt > property? I will try to use that driver for v2. Thx! > A dt property might make more sense if the syscon driver is to be used for multiple systems. Otherwise, no matter what you pick, it will be wrong for some system. Guenter