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Date: Mon, 21 Dec 2020 12:41:28 -0600
From: Bjorn Andersson <bjorn.andersson@...aro.org>
To: Ziqi Chen <ziqichen@...eaurora.org>
Cc: asutoshd@...eaurora.org, nguyenb@...eaurora.org,
cang@...eaurora.org, hongwus@...eaurora.org, rnayak@...eaurora.org,
vinholikatti@...il.com, jejb@...ux.vnet.ibm.com,
martin.petersen@...cle.com, linux-scsi@...r.kernel.org,
kernel-team@...roid.com, saravanak@...gle.com, salyzyn@...gle.com,
kwmad.kim@...sung.com, stanley.chu@...iatek.com,
Alim Akhtar <alim.akhtar@...sung.com>,
Avri Altman <avri.altman@....com>,
"James E.J. Bottomley" <jejb@...ux.ibm.com>,
Andy Gross <agross@...nel.org>,
Matthias Brugger <matthias.bgg@...il.com>,
Bean Huo <beanhuo@...ron.com>,
Bart Van Assche <bvanassche@....org>,
Adrian Hunter <adrian.hunter@...el.com>,
Satya Tangirala <satyat@...gle.com>,
"moderated list:UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER..."
<linux-mediatek@...ts.infradead.org>,
open list <linux-kernel@...r.kernel.org>,
"open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH RFC v3 1/1] scsi: ufs: Fix ufs power down/on specs
violation
On Mon 21 Dec 01:51 CST 2020, Ziqi Chen 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@...sung.com>
> Cc: Stanley Chu <stanley.chu@...iatek.com>
> Signed-off-by: Ziqi Chen <ziqichen@...eaurora.org>
> ---
> 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);
The comment above describes that the reset pulse should be 10uS, so the
only reason I can see for the sleep here would be for devices to come
back up after the reset pulse - i.e. what Mediatek believes needs
10-15mS.
As such, I would like you to move this sleep out to the caller and then
turns this snippet into just:
gpiod_set_value_cansleep(host->device_reset, down);
I don't see a problem using Mediatek's reasoning and sleep values in the
common case.
> + }
>
> 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);
"asserting device reset failed"
> + 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);
> +
> + 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");
Please use dev_dbg(), as this is only interesting to us when we're
actually debugging UFS related issues.
> + } else {
> + dev_err(hba->dev, "device reset pulling up failure: %d\n", err);
"deasserting device reset failed"
> }
> +
> 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);
I don't think "toggle" adds any value to the understanding of what this
function is expected to do, so I would prefer that you just keep it
"device_reset".
I also would prefer that you replace "down" with "asserted" - as this
avoids questions about active high/low etc from the API.
Thanks,
Bjorn
> 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
>
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