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.
