From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-x242.google.com (mail-pl0-x242.google.com [IPv6:2607:f8b0:400e:c01::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 40mrSk6QLwzF1R9 for ; Thu, 17 May 2018 22:38:30 +1000 (AEST) Received: by mail-pl0-x242.google.com with SMTP id c19-v6so2479044pls.6 for ; Thu, 17 May 2018 05:38:30 -0700 (PDT) Sender: Guenter Roeck Subject: Re: [PATCH 0/3] Add support to disable sensor groups in P9 To: Shilpasri G Bhat Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, stewart@linux.vnet.ibm.com References: <1521716075-807-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <20180515150205.GA29321@roeck-us.net> <2ceb6b30-60b7-d985-ee0d-6c5784eda273@linux.vnet.ibm.com> From: Guenter Roeck Message-ID: <56bba97b-c6ee-e7a1-136c-a2236437484a@roeck-us.net> Date: Thu, 17 May 2018 05:38:25 -0700 MIME-Version: 1.0 In-Reply-To: <2ceb6b30-60b7-d985-ee0d-6c5784eda273@linux.vnet.ibm.com> Content-Type: text/plain; charset=windows-1252; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 05/16/2018 11:10 PM, Shilpasri G Bhat wrote: > > > On 05/15/2018 08:32 PM, Guenter Roeck wrote: >> On Thu, Mar 22, 2018 at 04:24:32PM +0530, Shilpasri G Bhat wrote: >>> This patch series adds support to enable/disable OCC based >>> inband-sensor groups at runtime. The environmental sensor groups are >>> managed in HWMON and the remaining platform specific sensor groups are >>> managed in /sys/firmware/opal. >>> >>> The firmware changes required for this patch is posted below: >>> https://lists.ozlabs.org/pipermail/skiboot/2018-March/010812.html >>> >> >> Sorry for not getting back earlier. This is a tough one. >> > > Thanks for the reply. I have tried to answer your questions according to my > understanding below: > >> Key problem is that you are changing the ABI with those new attributes. >> On top of that, the attributes _do_ make some sense (many chips support >> enabling/disabling of individual sensors), suggesting that those or >> similar attributes may or even should at some point be added to the ABI. >> >> At the same time, returning "0" as measurement values when sensors are >> disabled does not seem like a good idea, since "0" is a perfectly valid >> measurement, at least for most sensors. > > I agree. > >> >> Given that, we need to have a discussion about adding _enable attributes to >> the ABI > >> what is the scope, > IIUC the scope should be RW and the attribute is defined for each supported > sensor group > That is _your_ need. I am not aware of any other chip where a per-sensor group attribute would make sense. The discussion we need has to extend beyond the need of a single chip. Guenter >> when should the attributes exist and when not, > We control this currently via device-tree > >> do we want/need power_enable or powerX_enable or both, and so on), and > We need power_enable right now > >> what to return if a sensor is disabled (such as -ENODATA). > -ENODATA sounds good. > > Thanks and Regards, > Shilpa > > Once we have an >> agreement, we can continue with an implementation. >> >> Guenter >> >>> Shilpasri G Bhat (3): >>> powernv:opal-sensor-groups: Add support to enable sensor groups >>> hwmon: ibmpowernv: Add attributes to enable/disable sensor groups >>> powernv: opal-sensor-groups: Add attributes to disable/enable sensors >>> >>> .../ABI/testing/sysfs-firmware-opal-sensor-groups | 34 ++++++ >>> Documentation/hwmon/ibmpowernv | 31 ++++- >>> arch/powerpc/include/asm/opal-api.h | 4 +- >>> arch/powerpc/include/asm/opal.h | 2 + >>> .../powerpc/platforms/powernv/opal-sensor-groups.c | 104 ++++++++++++----- >>> arch/powerpc/platforms/powernv/opal-wrappers.S | 1 + >>> drivers/hwmon/ibmpowernv.c | 127 +++++++++++++++++++-- >>> 7 files changed, 265 insertions(+), 38 deletions(-) >>> create mode 100644 Documentation/ABI/testing/sysfs-firmware-opal-sensor-groups >>> >>> -- >>> 1.8.3.1 >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > >