On 1/5/24 07:39, Phillip Susi wrote:
> When a disk is in SLEEP mode it can not respond to any
> commands. Instead of waking up the sleeping disk, fake the
> commands. The commands include:
>
> CHECK POWER
> FLUSH CACHE
> SLEEP
> STANDBY IMMEDIATE
> IDENTIFY
>
> If we konw the disk is sleeping, we don't need to wake it up
> to to find out if it is in standby, so just pretend it is in
> standby. While alseep, there's no dirty pages in the cache,
> so there's no need to flush it. There's no point in waking
> a disk from sleep just to put it back to sleep. We also have
> a cache of the IDENTIFY information so just return that
> instead of waking the disk.
What ? If you wake up the drive, it will not be in standby... So I do not get
your point here. Can you clarify ? What is the problem you are trying to solve
here ? Is it related to system or runtime suspend/resume ?
And no, not a chance we fake commands like this.
> ---
> drivers/ata/libata-core.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 1244da8f77e2..d9e889fa2881 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -5045,6 +5045,22 @@ void ata_qc_issue(struct ata_queued_cmd *qc)
>
> /* if device is sleeping, schedule reset and abort the link */
> if (unlikely(qc->dev->flags & ATA_DFLAG_SLEEPING)) {
> + if (unlikely(qc->tf.command == ATA_CMD_CHK_POWER ||
> + qc->tf.command == ATA_CMD_SLEEP ||
> + qc->tf.command == ATA_CMD_FLUSH ||
> + qc->tf.command == ATA_CMD_FLUSH_EXT ||
> + qc->tf.command == ATA_CMD_STANDBYNOW1 ||
> + (qc->tf.command == ATA_CMD_ID_ATA &&
> + !ata_tag_internal(qc->tag))))
> + {
> + /* fake reply to avoid waking drive */
> + qc->flags |= ATA_QCFLAG_RTF_FILLED;
> + qc->result_tf.nsect = 0;
> + if (qc->tf.command == ATA_CMD_ID_ATA)
> + sg_copy_from_buffer(qc->sg, 1, qc->dev->id, 2 * ATA_ID_WORDS);
> + ata_qc_complete(qc);
> + return;
> + }
> link->eh_info.action |= ATA_EH_RESET;
> ata_ehi_push_desc(&link->eh_info, "waking up from sleep");
> ata_link_abort(link);
--
Damien Le Moal
Western Digital Research
