RE: [PATCH RFC v3 1/1] scsi: ufs: Fix ufs power down/on specs violation

On 2020-12-22 10:04, Kiwoong Kim wrote:

quoted

quoted

As per specs, e.g, JESD220E chapter 7.2, while powering off/on the
ufs device, RST_N signal and REF_CLK signal should be between
VSS(Ground) and VCCQ/VCCQ2.

To flexibly control device reset line, re-name the function
ufschd_vops_device_reset(sturct ufs_hba *hba) to ufshcd_
vops_toggle_device_reset(sturct ufs_hba *hba, bool down). The new
parameter "bool down" is used to separate device reset line pulling
down from pulling up.

Cc: Kiwoong Kim <redacted>
Cc: Stanley Chu <redacted>
Signed-off-by: Ziqi Chen <redacted>
---
 drivers/scsi/ufs/ufs-mediatek.c | 27 +++++++++-----------------
 drivers/scsi/ufs/ufs-qcom.c     | 22 ++++++++++-----------
 drivers/scsi/ufs/ufshcd.c       | 43
++++++++++++++++++++++++++++++------

--

quoted

---
 drivers/scsi/ufs/ufshcd.h       | 10 +++++-----
 4 files changed, 56 insertions(+), 46 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-mediatek.c b/drivers/scsi/ufs/ufs-

mediatek.c index 80618af..bff2c42 100644

--- a/drivers/scsi/ufs/ufs-mediatek.c
+++ b/drivers/scsi/ufs/ufs-mediatek.c

@@ -841,27 +841,18 @@ static int ufs_mtk_link_startup_notify(struct

ufs_hba *hba,
 	return ret;
 }

-static int ufs_mtk_device_reset(struct ufs_hba *hba)
+static int ufs_mtk_toggle_device_reset(struct ufs_hba *hba, bool
down)
 {
 	struct arm_smccc_res res;

-	ufs_mtk_device_reset_ctrl(0, res);
-
-	/*
-	 * The reset signal is active low. UFS devices shall detect
-	 * more than or equal to 1us of positive or negative RST_n
-	 * pulse width.
-	 *
-	 * To be on safe side, keep the reset low for at least 10us.
-	 */
-	usleep_range(10, 15);
-
-	ufs_mtk_device_reset_ctrl(1, res);
-
-	/* Some devices may need time to respond to rst_n */
-	usleep_range(10000, 15000);
+	if (down) {
+		ufs_mtk_device_reset_ctrl(0, res);
+	} else {
+		ufs_mtk_device_reset_ctrl(1, res);

-	dev_info(hba->dev, "device reset done\n");
+		/* Some devices may need time to respond to rst_n */
+		usleep_range(10000, 15000);
+	}

 	return 0;
 }

@@ -1052,7 +1043,7 @@ static const struct ufs_hba_variant_ops

ufs_hba_mtk_vops = {
 	.suspend             = ufs_mtk_suspend,
 	.resume              = ufs_mtk_resume,
 	.dbg_register_dump   = ufs_mtk_dbg_register_dump,
-	.device_reset        = ufs_mtk_device_reset,
+	.toggle_device_reset        = ufs_mtk_toggle_device_reset,
 	.event_notify        = ufs_mtk_event_notify,
 };

diff --git a/drivers/scsi/ufs/ufs-qcom.c

b/drivers/scsi/ufs/ufs-qcom.c index 2206b1e..c2ccaa5 100644

--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c

@@ -1404,12 +1404,13 @@ static void ufs_qcom_dump_dbg_regs(struct

ufs_hba
*hba)  }

 /**
- * ufs_qcom_device_reset() - toggle the (optional) device reset line
+ * ufs_qcom_toggle_device_reset() - toggle the (optional) device
reset
+ line
  * @hba: per-adapter instance
+ * @down: pull down or pull up device reset line
  *
  * Toggles the (optional) reset line to reset the attached device.
  */
-static int ufs_qcom_device_reset(struct ufs_hba *hba)
+static int ufs_qcom_toggle_device_reset(struct ufs_hba *hba, bool
down)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);

@@ -1417,15 +1418,12 @@ static int ufs_qcom_device_reset(struct

ufs_hba
*hba)
 	if (!host->device_reset)
 		return -EOPNOTSUPP;

-	/*
-	 * The UFS device shall detect reset pulses of 1us, sleep for 10us
to
-	 * be on the safe side.
-	 */
-	gpiod_set_value_cansleep(host->device_reset, 1);
-	usleep_range(10, 15);
-
-	gpiod_set_value_cansleep(host->device_reset, 0);
-	usleep_range(10, 15);
+	if (down) {
+		gpiod_set_value_cansleep(host->device_reset, 1);
+	} else {
+		gpiod_set_value_cansleep(host->device_reset, 0);
+		usleep_range(10, 15);
+	}

 	return 0;
 }

@@ -1473,7 +1471,7 @@ static const struct ufs_hba_variant_ops

ufs_hba_qcom_vops = {
 	.suspend		= ufs_qcom_suspend,
 	.resume			= ufs_qcom_resume,
 	.dbg_register_dump	= ufs_qcom_dump_dbg_regs,
-	.device_reset		= ufs_qcom_device_reset,
+	.toggle_device_reset		= ufs_qcom_toggle_device_reset,
 	.config_scaling_param = ufs_qcom_config_scaling_param,
 	.program_key		= ufs_qcom_ice_program_key,
 };

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index e221add..2ee905f 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c

@@ -585,7 +585,20 @@ static void ufshcd_device_reset(struct ufs_hba

*hba)
{
 	int err;

-	err = ufshcd_vops_device_reset(hba);
+	err = ufshcd_vops_toggle_device_reset(hba, true);
+	if (err) {
+		dev_err(hba->dev, "device reset pulling down failure: %d\n",
err);
+		return;
+	}
+
+	/*
+	 * The reset signal is active low. The UFS device
+	 * shall detect reset pulses of 1us, sleep for at
+	 * least 10us to be on the safe side.
+	 */
+	usleep_range(10, 15);

Is there any point where UFS specification tells this explicitly?
I think this should be moved only if the number, i.e. 10 and 15  just
relies on hardware conditions.


Thanks.
Kiwoong Kim

Hi Kiwoong,

Thanks for your comment. JESD220E Line 610~611 "The UFS device shall
detect more than or equal to 1us of positive or negative RST_n pulse".
Both QCOM and Mediatek use 10~15us. What number do you think more
appropriate?

Best Regards,
Ziqi

With yours, all the SoC vendors should wait for around 10us unconditionally
even if there will be a possibility that some can use shorter period.
I see this as a sort of optimization point.


Thanks.
Kiwoong Kim

quoted

quoted

+	err = ufshcd_vops_toggle_device_reset(hba, false);

 	if (!err) {
 		ufshcd_set_ufs_dev_active(hba);

@@ -593,7 +606,11 @@ static void ufshcd_device_reset(struct ufs_hba

*hba)
 			hba->wb_enabled = false;
 			hba->wb_buf_flush_enabled = false;
 		}
+		dev_info(hba->dev, "device reset done\n");
+	} else {
+		dev_err(hba->dev, "device reset pulling up failure: %d\n",
err);
 	}
+
 	if (err != -EOPNOTSUPP)
 		ufshcd_update_evt_hist(hba, UFS_EVT_DEV_RESET, err);  } @@ -
8686,8 +8703,6 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum
ufs_pm_op pm_op)
 	if (ret)
 		goto set_dev_active;

-	ufshcd_vreg_set_lpm(hba);
-
 disable_clks:
 	/*
 	 * Call vendor specific suspend callback. As these callbacks may
access @@ -8703,6 +8718,9 @@ static int ufshcd_suspend(struct ufs_hba
*hba, enum ufs_pm_op pm_op)
 	 */
 	ufshcd_disable_irq(hba);

+	if (ufshcd_is_link_off(hba))
+		ufshcd_vops_toggle_device_reset(hba, true);
+
 	ufshcd_setup_clocks(hba, false);

 	if (ufshcd_is_clkgating_allowed(hba)) { @@ -8711,6 +8729,8 @@
static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 					hba->clk_gating.state);
 	}

+	ufshcd_vreg_set_lpm(hba);
+
 	/* Put the host controller in low power mode if possible */
 	ufshcd_hba_vreg_set_lpm(hba);
 	goto out;

@@ -8778,18 +8798,19 @@ static int ufshcd_resume(struct ufs_hba *hba,

enum ufs_pm_op pm_op)
 	old_link_state = hba->uic_link_state;

 	ufshcd_hba_vreg_set_hpm(hba);
+
+	ret = ufshcd_vreg_set_hpm(hba);
+	if (ret)
+		goto out;
+
 	/* Make sure clocks are enabled before accessing controller */
 	ret = ufshcd_setup_clocks(hba, true);
 	if (ret)
-		goto out;
+		goto disable_vreg;

 	/* enable the host irq as host controller would be active soon */
 	ufshcd_enable_irq(hba);

-	ret = ufshcd_vreg_set_hpm(hba);
-	if (ret)
-		goto disable_irq_and_vops_clks;
-
 	/*
 	 * Call vendor specific resume callback. As these callbacks may
access
 	 * vendor specific host controller register space call them when
the @@ -8797,7 +8818,7 @@ static int ufshcd_resume(struct ufs_hba
*hba, enum ufs_pm_op pm_op)
 	 */
 	ret = ufshcd_vops_resume(hba, pm_op);
 	if (ret)
-		goto disable_vreg;
+		goto disable_irq_and_vops_clks;

 	/* For DeepSleep, the only supported option is to have the link off
*/
 	WARN_ON(ufshcd_is_ufs_dev_deepsleep(hba)
&& !ufshcd_is_link_off(hba)); @@ -8864,8 +8885,6 @@ static int
ufshcd_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	ufshcd_link_state_transition(hba, old_link_state, 0);
 vendor_suspend:
 	ufshcd_vops_suspend(hba, pm_op);
-disable_vreg:
-	ufshcd_vreg_set_lpm(hba);
 disable_irq_and_vops_clks:
 	ufshcd_disable_irq(hba);
 	if (hba->clk_scaling.is_allowed)

@@ -8876,6 +8895,8 @@ static int ufshcd_resume(struct ufs_hba *hba,

enum ufs_pm_op pm_op)
 		trace_ufshcd_clk_gating(dev_name(hba->dev),
 					hba->clk_gating.state);
 	}
+disable_vreg:
+	ufshcd_vreg_set_lpm(hba);
 out:
 	hba->pm_op_in_progress = 0;
 	if (ret)

diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 9bb5f0e..dccc3eb 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h

@@ -319,7 +319,7 @@ struct ufs_pwr_mode_info {
  * @resume: called during host controller PM callback
  * @dbg_register_dump: used to dump controller debug information
  * @phy_initialization: used to initialize phys
- * @device_reset: called to issue a reset pulse on the UFS device
+ * @toggle_device_reset: called to change logic level of reset gpio

on
+ the UFS device
  * @program_key: program or evict an inline encryption key
  * @event_notify: called to notify important events
  */

@@ -350,7 +350,7 @@ struct ufs_hba_variant_ops {
 	int     (*resume)(struct ufs_hba *, enum ufs_pm_op);
 	void	(*dbg_register_dump)(struct ufs_hba *hba);
 	int	(*phy_initialization)(struct ufs_hba *);
-	int	(*device_reset)(struct ufs_hba *hba);
+	int	(*toggle_device_reset)(struct ufs_hba *hba, bool down);
 	void	(*config_scaling_param)(struct ufs_hba *hba,
 					struct devfreq_dev_profile *profile,
 					void *data);

@@ -1216,10 +1216,10 @@ static inline void

ufshcd_vops_dbg_register_dump(struct ufs_hba *hba)
 		hba->vops->dbg_register_dump(hba);
 }

-static inline int ufshcd_vops_device_reset(struct ufs_hba *hba)
+static inline int ufshcd_vops_toggle_device_reset(struct ufs_hba
*hba,
+bool down)
 {
-	if (hba->vops && hba->vops->device_reset)
-		return hba->vops->device_reset(hba);
+	if (hba->vops && hba->vops->toggle_device_reset)
+		return hba->vops->toggle_device_reset(hba, down);

 	return -EOPNOTSUPP;
 }
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum, a Linux Foundation Collaborative Project

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel