On Thu, Apr 17, 2025 at 08:08:00PM +0900, Damien Le Moal wrote: > On 4/17/25 12:37, Igor Pylypiv wrote: > > On Wed, Apr 16, 2025 at 05:42:38PM +0900, Damien Le Moal wrote: > >> With ATA devices supporting the CDL feature, using CDL requires that the > >> feature be enabled with a SET FEATURES command. This command is issued > >> as the translated command for the MODE SELECT command issued by > >> scsi_cdl_enable() when the user enables CDL through the device > >> cdl_enable sysfs attribute. > >> > >> However, the implementation of scsi_cdl_enable() always issues a MODE > >> SELECT command for ATA devices when the enable argument is true, even if > >> CDL is already enabled on the device. While this does not cause any > >> issue with using CDL descriptors with read/write commands (the CDL > >> feature will be enabled on the drive), issuing the MODE SELECT command > >> even when the device CDL feature is already enabled will cause a reset > >> of the ATA device CDL statistics log page (as defined in ACS, any CDL > >> enable action must reset the device statistics). > >> > >> Avoid this needless actions (and the implied statistics log page reset) > >> by modifying scsi_cdl_enable() to issue the MODE SELECT command to > >> enable CDL if and only if CDL is not reported as already enabled on the > >> device. > > > > Hi Damien, > > > > What happens when a drive spins up with CDL enabled? Last year you sent > > a patch to make sure that CDL gets disabled by default. Is that still > > the case? > > Yes, that is unchanged so that we keep being consistent with the fact that the > scsi layer starts with the sysfs cdl_enabled attribute set to false. So if an > ATA device starts with CDL enabled, it will be disabled. > > That does not cause any issue with the CDL statistics log page because that page > is not persistent and cleared) on power-on-reset events and this change has no > effect on that. The CDL statistics log page will always be cleared on boot/reboot. > Sounds good. Thank you for confirming, Damien! Reviewed-by: Igor Pylypiv <ipylypiv@xxxxxxxxxx> > > -- > Damien Le Moal > Western Digital Research
