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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EB151C6FD1D for ; Thu, 30 Mar 2023 13:12:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231890AbjC3NMS (ORCPT ); Thu, 30 Mar 2023 09:12:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231835AbjC3NMR (ORCPT ); Thu, 30 Mar 2023 09:12:17 -0400 Received: from mail.kapsi.fi (mail.kapsi.fi [IPv6:2001:67c:1be8::25]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3AAC7AD30; Thu, 30 Mar 2023 06:12:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=kapsi.fi; s=20161220; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID: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=Wf6MWb07ZNdojZiHGLU/UEUqS29HIvuV7xIdWH9ogCM=; b=TyTxXCYdiREo+cP3lUaBxvkN/8 tpK0TZMeXm/mhBjX0BvMy4tGzxhUeDjbqb7p2Iem87a7jkD59ToSTmpzLWUejh76EByNHNQxqYQJ2 Zsb0X+mEA5F40k5C8A48x+Yf6cuAkdpSo9smM3tzOF651z9ab/DvQM5ujQtHYHnXbe/M09vKKBjcP fT8nr3Ed/YxP/GVZomhy8GGyScU5GEgnxkOpSOlCZyVUnT5iNaUpiKMBui7v6fos/wY1JBtqVzao3 DqBsWt50eO6OlYFMUG5/XFC3K5Q+Hk85+DJFHb/90y17XvD/WeBT3Q3YywCEuKPuPDZqhpT/k/Ff+ 7is0QGcA==; Received: from 91-158-25-70.elisa-laajakaista.fi ([91.158.25.70] helo=[192.168.1.10]) by mail.kapsi.fi with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1phs4F-000xOs-GC; Thu, 30 Mar 2023 16:11:51 +0300 Message-ID: Date: Thu, 30 Mar 2023 16:11:50 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v2] thermal: tegra-bpmp: Handle offline zones Content-Language: en-US To: Daniel Lezcano , "Rafael J. Wysocki" , Amit Kucheria , Zhang Rui , Thierry Reding , Jonathan Hunter Cc: Mikko Perttunen , linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org References: <20230330094904.2589428-1-cyndis@kapsi.fi> <204e0435-c544-8727-e892-9fc69b8d691d@kapsi.fi> From: Mikko Perttunen In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 91.158.25.70 X-SA-Exim-Mail-From: cyndis@kapsi.fi X-SA-Exim-Scanned: No (on mail.kapsi.fi); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 3/30/23 15:36, Daniel Lezcano wrote: > On 30/03/2023 12:06, Mikko Perttunen wrote: >> On 3/30/23 13:03, Daniel Lezcano wrote: >>> On 30/03/2023 11:49, Mikko Perttunen wrote: >>>> From: Mikko Perttunen >>>> >>>> Thermal zones located in power domains may not be accessible when >>>> the domain is powergated. In this situation, reading the temperature >>>> will return -BPMP_EFAULT. When evaluating trips, BPMP will internally >>>> use -256C as the temperature for offline zones. >>> >>>> For smooth operation, for offline zones, return -EAGAIN when reading >>>> the temperature and allow registration of zones even if they are >>>> offline during probe. >>> >>> I think it makes more sense to check if the power domain associated >>> with the device is powered up and if not return -EPROBE_DEFER. >> >> The power domains in question are related to computer vision engines >> that only get powered on when in use, possibly never if the user >> doesn't run a computer vision workload on the system. We still want >> other thermal zones to be available. > > Ok, I see the point. > > I'm worried about the semantic of the errors returned, the translation > from BPMP_EFAULT to EAGAIN and the assumption it is a disabled (may be > forever) thermal zone. > > What does the documentation say for the error msg.rx.ret == -BPMP_EFAULT? > The documentation says Value | Description -------------- | ----------------------------------------- 0 | Temperature query succeeded. -#BPMP_EINVAL | Invalid request parameters. -#BPMP_ENOENT | No driver registered for thermal zone. -#BPMP_EFAULT | Problem reading temperature measurement. In practice, what BPMP_EFAULT means here is that the hardware has no indicated temperature for the zone, which really only happens if the power domain is powered off. Mikko > >>>> Signed-off-by: Mikko Perttunen >>>> --- >>>> v2: >>>> * Adjusted commit message. >>>> * Patch 2/2 dropped for now since it is more controversial, >>>>    and this patch is more critical. >>>> >>>>   drivers/thermal/tegra/tegra-bpmp-thermal.c | 9 ++++++++- >>>>   1 file changed, 8 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/thermal/tegra/tegra-bpmp-thermal.c >>>> b/drivers/thermal/tegra/tegra-bpmp-thermal.c >>>> index f5fd4018f72f..4ffc3bb3bf35 100644 >>>> --- a/drivers/thermal/tegra/tegra-bpmp-thermal.c >>>> +++ b/drivers/thermal/tegra/tegra-bpmp-thermal.c >>>> @@ -52,6 +52,8 @@ static int __tegra_bpmp_thermal_get_temp(struct >>>> tegra_bpmp_thermal_zone *zone, >>>>       err = tegra_bpmp_transfer(zone->tegra->bpmp, &msg); >>>>       if (err) >>>>           return err; >>>> +    if (msg.rx.ret == -BPMP_EFAULT) >>>> +        return -EAGAIN; >>>>       if (msg.rx.ret) >>>>           return -EINVAL; >>>> @@ -259,7 +261,12 @@ static int tegra_bpmp_thermal_probe(struct >>>> platform_device *pdev) >>>>           zone->tegra = tegra; >>>>           err = __tegra_bpmp_thermal_get_temp(zone, &temp); >>>> -        if (err < 0) { >>>> + >>>> +        /* >>>> +         * Sensors in powergated domains may temporarily fail to be >>>> read >>>> +         * (-EAGAIN), but will become accessible when the domain is >>>> powered on. >>>> +         */ >>>> +        if (err < 0 && err != -EAGAIN) { >>>>               devm_kfree(&pdev->dev, zone); >>>>               continue; >>>>           } >>> >> >