[PATCH v4 0/3] scsi: core: allow auto suspend override by low-level driver

[PATCH v4 0/3] scsi: core: allow auto suspend override by low-level driver

[Stanley Chu]

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.

This patchset allows runtime suspend parameters override within the LLD itself instead of waiting for userspace to control the power management, and make UFS as the first user of this capability.

v3 => v4:
- Change scsi_device->rpm_autosuspend_on to scsi_device->rpm_autosuspend (Bart)
- Make the comment of scsi_device->rpm_autosuspend more elaborate (Bart)

v2 => v3:
- Create a member indicating autosuspend delay for the same SCSI host in SCSI host template (Bart)
- Use separate variables to control different things, (Bart)
    (a) Whether or not runtime suspend is enabled at device creation time
    (b) The power management autosuspend delay

v1 => v2:
- Allow "zero" sdev->rpm_autosuspend_delay (Avri)
- Fix format of some lines (Avri)

Stanley Chu (3):
  scsi: core: allow auto suspend override by low-level driver
  scsi: ufs: override auto suspend tunables for ufs
  scsi: ufs-mediatek: enable auto suspend capability

 drivers/scsi/scsi_sysfs.c       |  3 ++-
 drivers/scsi/sd.c               |  4 ++++
 drivers/scsi/ufs/ufs-mediatek.c |  3 +++
 drivers/scsi/ufs/ufshcd.c       |  9 +++++++++
 drivers/scsi/ufs/ufshcd.h       | 10 ++++++++++
 include/scsi/scsi_device.h      |  3 ++-
 include/scsi/scsi_host.h        |  3 +++
 7 files changed, 33 insertions(+), 2 deletions(-)

-- 
2.18.0

[PATCH v4 1/3] scsi: core: allow auto suspend override by low-level driver

[Stanley Chu]

Rework from previous work by:
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: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/scsi_sysfs.c  | 3 ++-
 drivers/scsi/sd.c          | 4 ++++
 include/scsi/scsi_device.h | 3 ++-
 include/scsi/scsi_host.h   | 3 +++
 4 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 64c96c7828ee..cebb9336c02b 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1300,7 +1300,8 @@ 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->rpm_autosuspend)
+		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 149d406aacc9..7358d2b0b2d2 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3371,6 +3371,10 @@ static int sd_probe(struct device *dev)
 	}
 
 	blk_pm_runtime_init(sdp->request_queue, dev);
+	if (sdp->rpm_autosuspend) {
+		pm_runtime_set_autosuspend_delay(dev,
+			sdp->host->hostt->rpm_autosuspend_delay);
+	}
 	device_add_disk(dev, gd, NULL);
 	if (sdkp->capacity)
 		sd_dif_config_host(sdkp);
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 202f4d6a4342..039e289f295e 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -199,7 +199,8 @@ 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 rpm_autosuspend:1;	/* Enable runtime autosuspend at device
+					 * creation time */
 	atomic_t disk_events_disable_depth; /* disable depth for disk events */
 
 	DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index cc139dbd71e5..3cb64f0a7e3a 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -474,6 +474,9 @@ struct scsi_host_template {
 	 */
 	unsigned int cmd_size;
 	struct scsi_host_cmd_pool *cmd_pool;
+
+	/* Delay for runtime autosuspend */
+	int rpm_autosuspend_delay;
 };
 
 /*
-- 
2.18.0

[PATCH v4 2/3] scsi: ufs: override auto suspend tunables for ufs

[Stanley Chu]

Rework from previous work by:
Sujit Reddy Thumma <sthumma@codeaurora.org>

Override auto suspend tunables for UFS device LUNs during
initialization so as to efficiently manage background operations
and the power consumption.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
---
 drivers/scsi/ufs/ufshcd.c |  9 +++++++++
 drivers/scsi/ufs/ufshcd.h | 10 ++++++++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 30b752c61b97..60a24fe908e7 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -88,6 +88,9 @@
 /* Interrupt aggregation default timeout, unit: 40us */
 #define INT_AGGR_DEF_TO	0x02
 
+/* default delay of autosuspend: 2000 ms */
+#define RPM_AUTOSUSPEND_DELAY_MS 2000
+
 #define ufshcd_toggle_vreg(_dev, _vreg, _on)				\
 	({                                                              \
 		int _ret;                                               \
@@ -4612,9 +4615,14 @@ static int ufshcd_change_queue_depth(struct scsi_device *sdev, int depth)
  */
 static int ufshcd_slave_configure(struct scsi_device *sdev)
 {
+	struct ufs_hba *hba = shost_priv(sdev->host);
 	struct request_queue *q = sdev->request_queue;
 
 	blk_queue_update_dma_pad(q, PRDT_DATA_BYTE_COUNT_PAD - 1);
+
+	if (ufshcd_is_rpm_autosuspend_allowed(hba))
+		sdev->rpm_autosuspend = 1;
+
 	return 0;
 }
 
@@ -7041,6 +7049,7 @@ static struct scsi_host_template ufshcd_driver_template = {
 	.track_queue_depth	= 1,
 	.sdev_groups		= ufshcd_driver_groups,
 	.dma_boundary		= PAGE_SIZE - 1,
+	.rpm_autosuspend_delay	= RPM_AUTOSUSPEND_DELAY_MS,
 };
 
 static int ufshcd_config_vreg_load(struct device *dev, struct ufs_vreg *vreg,
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index a43c7135f33d..99ea416519af 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -714,6 +714,12 @@ struct ufs_hba {
 	 * the performance of ongoing read/write operations.
 	 */
 #define UFSHCD_CAP_KEEP_AUTO_BKOPS_ENABLED_EXCEPT_SUSPEND (1 << 5)
+	/*
+	 * This capability allows host controller driver to automatically
+	 * enable runtime power management by itself instead of waiting
+	 * for userspace to control the power management.
+	 */
+#define UFSHCD_CAP_RPM_AUTOSUSPEND (1 << 6)
 
 	struct devfreq *devfreq;
 	struct ufs_clk_scaling clk_scaling;
@@ -747,6 +753,10 @@ static inline bool ufshcd_can_autobkops_during_suspend(struct ufs_hba *hba)
 {
 	return hba->caps & UFSHCD_CAP_AUTO_BKOPS_SUSPEND;
 }
+static inline bool ufshcd_is_rpm_autosuspend_allowed(struct ufs_hba *hba)
+{
+	return hba->caps & UFSHCD_CAP_RPM_AUTOSUSPEND;
+}
 
 static inline bool ufshcd_is_intr_aggr_allowed(struct ufs_hba *hba)
 {
-- 
2.18.0

[PATCH v4 3/3] scsi: ufs-mediatek: enable auto suspend capability

[Stanley Chu]

Enable auto suspend capability in MediaTek UFS driver.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufs-mediatek.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/scsi/ufs/ufs-mediatek.c b/drivers/scsi/ufs/ufs-mediatek.c
index 0f6ff33ce52e..83e28edc3ac5 100644
--- a/drivers/scsi/ufs/ufs-mediatek.c
+++ b/drivers/scsi/ufs/ufs-mediatek.c
@@ -147,6 +147,9 @@ static int ufs_mtk_init(struct ufs_hba *hba)
 	if (err)
 		goto out_variant_clear;
 
+	/* Enable runtime autosuspend */
+	hba->caps |= UFSHCD_CAP_RPM_AUTOSUSPEND;
+
 	/*
 	 * ufshcd_vops_init() is invoked after
 	 * ufshcd_setup_clock(true) in ufshcd_hba_init() thus
-- 
2.18.0

Re: [PATCH v4 0/3] scsi: core: allow auto suspend override by low-level driver

[Martin K. Petersen]

Stanley,

> 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.

Applied to 5.5/scsi-queue, thank you!

-- 
Martin K. Petersen	Oracle Linux Engineering