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SubjectRe: [PATCH v1 2/9] scsi: Allow auto suspend override by low-level driver
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On 06/07/18 15:30, Asutosh Das wrote:
> From: Sujit Reddy Thumma <sthumma@codeaurora.org>
>
> Until now the scsi mid-layer forbids runtime suspend till userspace
> enables it. This is mainly to quarantine some disks with broken
> runtime power management or have high latencies executing suspend
> resume callbacks. If the userspace doesn't enable the runtime suspend
> the underlying hardware will be always on even when it is not doing
> any useful work and thus wasting power.
>
> Some low-level drivers for the controllers can efficiently use runtime
> power management to reduce power consumption and improve battery life.
> Allow runtime suspend parameters override within the LLD itself
> instead of waiting for userspace to control the power management.
>
> Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
> Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>

Notwithstanding one minor comment below:

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
> drivers/scsi/scsi_scan.c | 4 ++++
> drivers/scsi/scsi_sysfs.c | 3 ++-
> drivers/scsi/sd.c | 2 ++
> include/scsi/scsi_device.h | 3 +++
> 4 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index 0880d97..5b7232a 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -969,6 +969,10 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
>
> transport_configure_device(&sdev->sdev_gendev);
>
> + /* The LLD can override auto suspend tunables in ->slave_configure() */
> + sdev->use_rpm_auto = 0;
> + sdev->autosuspend_delay = SCSI_DEFAULT_AUTOSUSPEND_DELAY;
> +
> if (sdev->host->hostt->slave_configure) {
> ret = sdev->host->hostt->slave_configure(sdev);
> if (ret) {
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index 7943b76..706e778 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -1266,7 +1266,8 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
> device_enable_async_suspend(&sdev->sdev_gendev);
> scsi_autopm_get_target(starget);
> pm_runtime_set_active(&sdev->sdev_gendev);
> - pm_runtime_forbid(&sdev->sdev_gendev);
> + if (!sdev->use_rpm_auto)
> + pm_runtime_forbid(&sdev->sdev_gendev);
> pm_runtime_enable(&sdev->sdev_gendev);
> scsi_autopm_put_target(starget);
>
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index a6201e6..205624f 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -3269,6 +3269,8 @@ static void sd_probe_async(void *data, async_cookie_t cookie)
> }
>
> blk_pm_runtime_init(sdp->request_queue, dev);
> + if (sdp->autosuspend_delay >= 0)
> + pm_runtime_set_autosuspend_delay(dev, sdp->autosuspend_delay);

Wouldn't it be nicer to pass the autosuspend_delay into blk_pm_runtime_init()?

> device_add_disk(dev, gd);
> if (sdkp->capacity)
> sd_dif_config_host(sdkp);
> diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
> index 4c36af6..1d5ae90 100644
> --- a/include/scsi/scsi_device.h
> +++ b/include/scsi/scsi_device.h
> @@ -197,7 +197,10 @@ struct scsi_device {
> unsigned broken_fua:1; /* Don't set FUA bit */
> unsigned lun_in_cdb:1; /* Store LUN bits in CDB[1] */
> unsigned unmap_limit_for_ws:1; /* Use the UNMAP limit for WRITE SAME */
> + unsigned use_rpm_auto:1; /* Enable runtime PM auto suspend */
>
> +#define SCSI_DEFAULT_AUTOSUSPEND_DELAY -1
> + int autosuspend_delay;
> atomic_t disk_events_disable_depth; /* disable depth for disk events */
>
> DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */
>

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