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Message-ID: <34212690167dbcde23a9ff347b3578ad@codeaurora.org>
Date: Tue, 22 Dec 2020 11:08:52 +0800
From: ziqichen@...eaurora.org
To: Bjorn Andersson <bjorn.andersson@...aro.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 2020-12-22 02:41, Bjorn Andersson wrote:
> 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.
Understood. It would better to move this sleep (10-15ms)out to the
caller and
simplify this function.
>
>> + }
>>
>> 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"
Agree, thanks.
>
>> + 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.
Agree, thanks.
>
>> + } else {
>> + dev_err(hba->dev, "device reset pulling up failure: %d\n", err);
>
> "deasserting device reset failed"
Agree, thanks.
>
>> }
>> +
>> 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
Agree, thanks.
Best Regards,
Ziqi
>
>> 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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