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([2a0e:5700:4:11:334c:7e36:8d57:40cb]) by smtp.gmail.com with ESMTPSA id j21-20020aa7c415000000b004127ac9ddc3sm1866517edq.50.2022.02.25.13.19.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Feb 2022 13:19:20 -0800 (PST) Message-ID: <7ab071a2-4e5e-9aea-6887-d3e4281de607@redhat.com> Date: Fri, 25 Feb 2022 22:19:15 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH v2 1/3] ata: ahci: Rename board_ahci_mobile Content-Language: en-US To: "Limonciello, Mario" , Christoph Hellwig Cc: Damien Le Moal , "open list:LIBATA SUBSYSTEM (Serial and Parallel ATA drivers)" , open list , "pmenzel@molgen.mpg.de" References: <20220225061113.223920-1-mario.limonciello@amd.com> From: Hans de Goede In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2/25/22 22:13, Limonciello, Mario wrote: > [AMD Official Use Only] > >>>>>> On Fri, Feb 25, 2022 at 12:11:11AM -0600, Mario Limonciello wrote: >>>>>>> This board definition was originally created for mobile devices to >>>>>>> designate default link power managmeent policy to influence runtime >>>>>>> power consumption. >>>>>>> >>>>>>> As this is interesting for more than just mobile designs, rename the >>>>>>> board to `board_ahci_low_power` to make it clear it is about default >>>>>>> policy. >>>>>> >>>>>> Is there any good reason to not just apply the policy to all devices >>>>>> by default? >>>>> >>>>> That sure would make this all cleaner. >>>>> >>>>> I think Hans knows more of the history here than anyone else. I had >>>>> presumed there was some data loss scenarios with some of the older >>>>> chipsets. >>>> >>>> When I first introduced this change there were reports of crashes and >>>> data corruption caused by setting the policy to min_power, these were >>>> tied to some motherboards and/or to some drives. >>>> >>>> This is the whole reason why I only enabled this on a subset of all the >>>> AHCI chipsets. >>>> >>>> At least on devices with a chipset which is currently marked as >>>> mobile, the motherboard specific issues could be fixed with a BIOS >>>> update. But I doubt that similar BIOS fixes have also been rolled >>>> out to all desktop boards (and have been applied by all users), >>>> and I also don't know about older boards. >>>> >>>> So enabling this on all chipsets is definitely not without risks. >>>> >>> >>> This was before min_power_with_partial and min_power_with_dipm >>> were introduced though right? >> >> The issues where some laptops needed BIOS updates was with fedora >> using min_power_with_dipm as default for mobile chipsets. >> > > Do you know if the drives actually supported slumber and partial? > I wonder if that was the real problem that they were being set when > they shouldn't be.> > I added something for this in 2/2 in the RFC series you can look at. Fedora defaults to ATA_LPM_MED_POWER_WITH_DIPM so patch 2/2 is a no-op on Fedora; and IIRC (it has been a long time) the need for BIOS updates on some mobile devices was with standard Fedora kernels / settings. Regards, Hans > >>> Maybe another way to look at this >>> is to drop the policy min_power, which overall is dangerous. >> >> Maybe, see above. I'm not going to block this if people want >> to give this a try, but it is going to require someone keeping >> a very close look at any issues popping up and we must be >> prepared to roll-back the change if necessary. >> > > Per Paul's suggestion I sent out v3 of this series and then I sent > out a separate RFC series (you're on CC). For this type of > thing if y'all think it makes sense to do.