Re: [PATCH v2] ata: libata-scsi: Fix CDL control

[Niklas Cassel <cassel@kernel.org>]

On Wed, Aug 13, 2025 at 07:22:56PM -0700, Igor Pylypiv wrote:
> Delete extra checks for the ATA_DFLAG_CDL_ENABLED flag that prevent
> SET FEATURES command from being issued to a drive when NCQ commands
> are active.
> 
> ata_mselect_control_ata_feature() sets / clears the ATA_DFLAG_CDL_ENABLED
> flag during the translation of MODE SELECT to SET FEATURES. If SET FEATURES
> gets deferred due to outstanding NCQ commands, the original MODE SELECT
> command will be re-queued. When the re-queued MODE SELECT goes through
> the ata_mselect_control_ata_feature() translation again, SET FEATURES
> will not be issued because ATA_DFLAG_CDL_ENABLED has been already set or
> cleared by the initial translation of MODE SELECT.
> 
> The ATA_DFLAG_CDL_ENABLED checks in ata_mselect_control_ata_feature()
> are safe to remove because scsi_cdl_enable() implements a similar logic
> that avoids enabling CDL if it has been enabled already.
> 
> Fixes: 17e897a45675 ("ata: libata-scsi: Improve CDL control")
> Signed-off-by: Igor Pylypiv <ipylypiv@google.com>

Reviewed-by: Niklas Cassel <cassel@kernel.org>

However, like Damien said, we really need to improve the API so that the
SAT can know if the command was success or failure.

That way we could set the flag only after the command was successful.


Kind regards,
Niklas