Re: [PATCH 0/1] Summary: hwmon driver for temperature sensors on SATA drives

From: Damien Le Moal <Damien.LeMoal@wdc.com>
To: Guenter Roeck <linux@roeck-us.net>,
	"Martin K. Petersen" <martin.petersen@oracle.com>
Cc: "linux-hwmon@vger.kernel.org" <linux-hwmon@vger.kernel.org>,
	Jean Delvare <jdelvare@suse.com>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"linux-ide@vger.kernel.org" <linux-ide@vger.kernel.org>
Subject: Re: [PATCH 0/1] Summary: hwmon driver for temperature sensors on SATA drives
Date: Tue, 17 Dec 2019 05:50:17 +0000	[thread overview]
Message-ID: <BYAPR04MB5816CA0C1CAFC21F7955F79FE7500@BYAPR04MB5816.namprd04.prod.outlook.com> (raw)
In-Reply-To: 83d528fc-42b7-aa3f-5dd9-a000268da38e@roeck-us.net

On 2019/12/17 12:57, Guenter Roeck wrote:
> On 12/16/19 6:35 PM, Martin K. Petersen wrote:
>>
>> Guenter,
>>
>>> If and when drives are detected which report bad information, such
>>> drives can be added to a blacklist without impact on the core SCSI or
>>> ATA code. Until that happens, not loading the driver solves the
>>> problem on any affected system.
>>
>> My only concern with that is that we'll have blacklisting several
>> places. We already have ATA and SCSI blacklists. If we now add a third
>> place, that's going to be a maintenance nightmare.
>>
>> More on that below.
>>
>>>> My concerns are wrt. identifying whether SMART data is available for
>>>> USB/UAS. I am not too worried about ATA and "real" SCSI (ignoring RAID
>>>> controllers that hide the real drives in various ways).
>>
>> OK, so I spent my weekend tinkering with 15+ years of accumulated USB
>> devices. And my conclusion is that no, we can't in any sensible manner,
>> support USB storage monitoring in the kernel. There is no heuristic that
>> I can find that identifies that "this is a hard drive or an SSD and
>> attempting one of the various SMART methods may be safe". As opposed to
>> "this is a USB key that's likely to lock up if you try". And that's
>> ignoring the drives with USB-ATA bridges that I managed to wedge in my
>> attempt at sending down commands.
>>
>> Even smartmontools is failing to work on a huge part of my vintage
>> collection.  Thanks to a wide variety of bridges with random, custom
>> interfaces.
>>
>> So my stance on all this is that I'm fine with your general approach for
>> ATA. I will post a patch adding the required bits for SCSI. And if a
>> device does not implement either of the two standard methods, people
>> should use smartmontools.
>>
>> Wrt. name, since I've added SCSI support, satatemp is a bit of a
>> misnomer. drivetemp, maybe? No particular preference.
>>
> Agreed, if we extend this to SCSI, satatemp is less than perfect.
> drivetemp ? disktemp ? I am open to suggestions, with maybe a small
> personal preference for disktemp out of those two.

"disk" tend to imply HDD, excluding SSDs. So my vote goes to
"drivetemp", or even the more generic, "devtemp".

-- 
Damien Le Moal
Western Digital Research