On 8/14/25 5:46 AM, Igor Pylypiv wrote:
> This reverts commit 17e897a456752ec9c2d7afb3d9baf268b442451b.
A full revert is not nice. See below.
Also please change the patch title to:
ata: libata-scsi: Fix CDL control
Or similar.
And do not send the patch to stable@xxxxxxxxxxxxxxx. It will be picked up if
you add the Fixes tag (see below).
>
> The extra checks for the ATA_DFLAG_CDL_ENABLED flag 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 already enabled.
>
Please add "Fixes: 17e897a45675 ("ata: libata-scsi: Improve CDL control") here.
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Igor Pylypiv <ipylypiv@xxxxxxxxxx>
> ---
> drivers/ata/libata-scsi.c | 14 ++------------
> 1 file changed, 2 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index 57f674f51b0c..856eabfd5a17 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -3904,27 +3904,17 @@ static int ata_mselect_control_ata_feature(struct ata_queued_cmd *qc,
> /* Check cdl_ctrl */
> switch (buf[0] & 0x03) {
> case 0:
> - /* Disable CDL if it is enabled */
> - if (!(dev->flags & ATA_DFLAG_CDL_ENABLED))
> - return 0;
> - ata_dev_dbg(dev, "Disabling CDL\n");
Please keep this debug message and move it below the comment.
> + /* Disable CDL */
> cdl_action = 0;
> dev->flags &= ~ATA_DFLAG_CDL_ENABLED;
> break;
> case 0x02:
> - /*
> - * Enable CDL if not already enabled. Since this is mutually
> - * exclusive with NCQ priority, allow this only if NCQ priority
> - * is disabled.
> - */
> - if (dev->flags & ATA_DFLAG_CDL_ENABLED)
> - return 0;
> + /* Enable CDL T2A/T2B: NCQ priority must be disabled */
T2A/T2B is for SCSI, not ATA. So let's not mention that. I prefer that the
comment keeps the "mutually exclusive" mention, so something like:
*
* Enable CDL. Since this is mutually exclusive with the NCQ
* priority feature set, allow this only if NCQ priority is
* disabled.
*/
> if (dev->flags & ATA_DFLAG_NCQ_PRIO_ENABLED) {
> ata_dev_err(dev,
> "NCQ priority must be disabled to enable CDL\n");
> return -EINVAL;
> }
> - ata_dev_dbg(dev, "Enabling CDL\n");
And please keep this debug message.
> cdl_action = 1;
> dev->flags |= ATA_DFLAG_CDL_ENABLED;
> break;
--
Damien Le Moal
Western Digital Research
