On Wed, Feb 14, 2018 at 04:03:17PM +0100, Hans de Goede wrote: > Hi All, > > On 14-02-18 15:25, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > > > This is a note to let you know that I've just added the patch titled > > > > ahci: Allow setting a default LPM policy for mobile chipsets > > > > to the 4.14-stable tree which can be found at: > > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > > > The filename of the patch is: > > ahci-allow-setting-a-default-lpm-policy-for-mobile-chipsets.patch > > and it can be found in the queue-4.14 subdirectory. > > > > If you, or anyone else, feels it should not be added to the stable tree, > > please let <stable@xxxxxxxxxxxxxxx> know about it. > > I wonder how this ended up on the patches-for-stable list? Torvald's > master commits have neither a Cc: stable or a Fixes tag. > > By itself this series is harmless, until someone actually sets > the new Kconfig option to something other then 0. See my response to the 4.15.y patch for "how" this came to be merged. > > +config SATA_MOBILE_LPM_POLICY > > + int "Default SATA Link Power Management policy for mobile chipsets" > > + range 0 4 > > + default 0 > > + depends on SATA_AHCI > > + help > > + Select the Default SATA Link Power Management (LPM) policy to use > > + for mobile / laptop variants of chipsets / "South Bridges". > > + > > + The value set has the following meanings: > > + 0 => Keep firmware settings > > + 1 => Maximum performance > > + 2 => Medium power > > + 3 => Medium power with Device Initiated PM enabled > > + 4 => Minimum power > > + > > + Note "Minimum power" is known to cause issues, including disk > > + corruption, with some disks and should not be used. > > + > > AFAIK 4.14 and older do not have med_power_with_dipm, so setting this > to 3 will lead to a setting of min_power. Which leads me to my worry > about this series, as said in itself it is harmless, but as the help > text says setting it to 4 (*) is dangerous. Actually this week I've > received my first bug report that even med_power_with_dipm is causing > issues (disconnects) with some devices. I'm working with the reporter > an a blacklist entry for the specific SSD in question, but given that > we're still figuring this out for master I wonder how wise it is to > add these to stable, esp. since stable lacks med_power_with_dipm. > > At a minimum we should fixup the help-text for 4.14 and older > (4.15 does have med_power_with_dipm). What would the text be for 4.14.y and older? I'll be glad to fix that up. Or I can drop the whole thing and fit in the device id update "by hand", if you think this shouldn't go to the stable trees. thanks, greg k-h