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

[Kiwoong Kim]

> On 2020-12-22 10:04, Kiwoong Kim wrote:
> >> 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 <kwmad.kim@xxxxxxxxxxx>
> >> Cc: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
> >> Signed-off-by: Ziqi Chen <ziqichen@xxxxxxxxxxxxxx>
> >> ---
> >>  drivers/scsi/ufs/ufs-mediatek.c | 27 +++++++++-----------------
> >>  drivers/scsi/ufs/ufs-qcom.c     | 22 ++++++++++-----------
> >>  drivers/scsi/ufs/ufshcd.c       | 43
> >> ++++++++++++++++++++++++++++++------
> > --
> >> ---
> >>  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
> 
> >
> >> +	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