From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23CBAC43142 for ; Wed, 27 Jun 2018 18:33:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C08E125EC6 for ; Wed, 27 Jun 2018 18:33:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=roeck-us.net header.i=@roeck-us.net header.b="KSeq6gs4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C08E125EC6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=roeck-us.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965877AbeF0Sdc (ORCPT ); Wed, 27 Jun 2018 14:33:32 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:44361 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754551AbeF0Sda (ORCPT ); Wed, 27 Jun 2018 14:33:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=roeck-us.net; s=default; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=i2lQWvZkogLF9B8XHBOXgWXtrgleDo7HUpkCnaMbO6Y=; b=KSeq6gs4H4Tx21bTKdziRi+W6t O+bHguRQwppy09oTJ2wDrI+LRBFH3S8uVVRZJ/S8tyM6wnq6OFXjJ89Z2ZbZ1lodb+B9d1r+Y+kfY okoG8DPOoHb1II4/SRpyWPApyixwUmG1Nupi1ZQlQTHmgwW05zlX+rv2Wk7mKgKrib2V4sYaD1gWe HZthb2hfJOUngMORJKPDJU5BB0jdkraBZWwFUIdjx08OIl23ZWJoT0QX3qdVEjKulUfTotxqfnZub M3jwfxW3J00zyKWgB/OtwNaUU+peZto6thdqEz/oxua2TIf2OB4O3nXMkF6rkoW97B5udlxgtcNlh UeZH8Evw==; Received: from 108-223-40-66.lightspeed.sntcca.sbcglobal.net ([108.223.40.66]:38716 helo=localhost) by bh-25.webhostbox.net with esmtpa (Exim 4.89) (envelope-from ) id 1fYFFw-00FXtO-22; Wed, 27 Jun 2018 18:33:28 +0000 Date: Wed, 27 Jun 2018 11:33:27 -0700 From: Guenter Roeck To: Ray Jui Cc: Rob Herring , Wim Van Sebroeck , Mark Rutland , Frank Rowand , Catalin Marinas , Will Deacon , Robin Murphy , linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel , Linux Kernel Mailing List , BCM Kernel Feedback Subject: Re: [PATCH v4 1/6] Documentation: DT: Consolidate SP805 binding docs Message-ID: <20180627183327.GD16753@roeck-us.net> References: <1527530497-10392-1-git-send-email-ray.jui@broadcom.com> <1527530497-10392-2-git-send-email-ray.jui@broadcom.com> <20180605194124.GA26885@rob-hp-laptop> <09c870cd-0a44-6634-58d8-f57f9fcd0cb5@broadcom.com> <46ca340f-4347-94ca-6463-d38bece820e2@broadcom.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <46ca340f-4347-94ca-6463-d38bece820e2@broadcom.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 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: authenticated_id: guenter@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: guenter@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 20, 2018 at 10:39:16AM -0700, Ray Jui wrote: > Hi Guenter/Rob, > > Kindly let me know how you want to proceed with this? > If I recall correctly, the patch series does not add a new problem but merely exposes one. Is my recollection correct ? If so, maybe we should just add a note somewhere indicating what might be wrong and otherwise apply the series. Does this make sense ? Guenter > Thanks, > > Ray > > On 6/6/2018 4:39 PM, Ray Jui wrote: > > > > > >On 6/6/2018 9:33 AM, Rob Herring wrote: > >>On Wed, Jun 6, 2018 at 11:19 AM, Guenter Roeck > >>wrote: > >>>On 06/05/2018 12:41 PM, Rob Herring wrote: > >>>> > >>>>On Mon, May 28, 2018 at 11:01:32AM -0700, Ray Jui wrote: > >>>>> > >>>>>Consolidate two SP805 binding documents "arm,sp805.txt" and > >>>>>"sp805-wdt.txt" into "arm,sp805.txt" that matches the naming of the > >>>>>desired compatible string to be used > >>>>> > >>>>>Signed-off-by: Ray Jui > >>>>>--- > >>>>>   .../devicetree/bindings/watchdog/arm,sp805.txt     | 27 > >>>>>++++++++++++++----- > >>>>>   .../devicetree/bindings/watchdog/sp805-wdt.txt     | 31 > >>>>>---------------------- > >>>>>   2 files changed, 20 insertions(+), 38 deletions(-) > >>>>>   delete mode 100644 > >>>>>Documentation/devicetree/bindings/watchdog/sp805-wdt.txt > >>>> > >>>> > >>>>Would be good to get a ACK from FSL/NXP person on this. It looks to me > >>>>like the driver fetches the wrong clock as it gets the first one and > >>>>the > >>>>driver really wants 'wdog_clk'. In any case, their dts files should be > >>>>updated. > >>>> > >>> > >>>This is really confusing, since he deleted file lists apb_pclk first. > >>>Does the watchdog driver need apb_pclk or wdog_clk ? That isn't clear > >>>to me. > >>>arch/arm64/boot/dts/hisilicon/hi3660.dtsi only provides apb_pclk, or at > >>>least > >>>it says so. > >> > >>Note that that clock source is 32KHz. That is obviously a mistake > >>because no one clocks their bus/register interface at 32KHz. Someone > >>just filled in something that happened to work. > >> > >>>The fsl dts files all have apb_pclk first. > >> > >>It's all kind of a mess, but fortunately one we should be able to > >>clean-up. > >> > > > >It is indeed a mess. Note the SP805 driver only derive one clock from DT, > >and that's not done based on name. As a result, the first clock defined in > >DT will be fetched and the rate calculation will be carried out based on > >that clock rate. > > > >I assumed the clock entries and their names defined in the binding > >document are just placeholders, at least for the 2nd clock. > > > >Based on how the current driver is, the first clock needs to be the > >WDOGCLK for things to work properly. > > > >According to the SP805 TRM, APB clock is the PCLK, that drives the bus for > >register access. > > > >The relationship between WDOGCLK and PCLK is defined as: > > > >- the rising edges of WDOGCLK must be synchronous and > >balanced with a rising edge of PCLK > > > >- the WDOGCLK frequency cannot be greater than the PCLK > >frequency > > > >>The compatible string changes too, but AMBA bus devices don't actually > >>use the compatible string as they use the ID registers to match. I > >>suppose some other OS could do things differently. Worth the risk to > >>clean-up IMO. > >> > >>> > >>>Either case, why are two clocks asked for in the first place ? Are there > >>>situations where the second clock is actually used/useful ? > >> > >>For clocks, the bus needs "apb_pclk" and the driver just gets the > >>first clock. The driver is obviously going to want the functional > >>clock that determines the counter rate. That should > >> > >>Primecell peripherals are about the only ones that have clear specs > >>WRT clock inputs. Yet we've still managed to screw them up. There are > >>2 clocks in the spec, so the DT has (or should have) 2 clocks. > >> > >>Rob > >> > > > >Let me know how you guys want to proceed with this? > > > >Thanks, > > > >Ray > -- > To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html