Messages in this thread | | | Date | Tue, 29 Dec 2020 09:18:11 +0800 | From | Can Guo <> | Subject | Re: [PATCH RFC v4 1/1] scsi: ufs: Fix ufs power down/on specs violation |
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On 2020-12-29 01:55, Bjorn Andersson wrote: > On Tue 22 Dec 07:49 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, refactor the function >> ufschd_vops_device_reset(sturct ufs_hba *hba) to ufshcd_ >> vops_device_reset(sturct ufs_hba *hba, bool asserted). The >> new parameter "bool asserted" is used to separate device reset >> line pulling down from pulling up. >> >> Cc: Kiwoong Kim <kwmad.kim@samsung.com> >> Cc: Stanley Chu <stanley.chu@mediatek.com> >> Signed-off-by: Ziqi Chen <ziqichen@codeaurora.org> >> --- >> drivers/scsi/ufs/ufs-mediatek.c | 32 ++++++++++++++++---------------- >> drivers/scsi/ufs/ufs-qcom.c | 24 +++++++++++++++--------- >> drivers/scsi/ufs/ufshcd.c | 36 >> +++++++++++++++++++++++++----------- >> drivers/scsi/ufs/ufshcd.h | 8 ++++---- >> 4 files changed, 60 insertions(+), 40 deletions(-) >> >> diff --git a/drivers/scsi/ufs/ufs-mediatek.c >> b/drivers/scsi/ufs/ufs-mediatek.c >> index 80618af..072f4db 100644 >> --- a/drivers/scsi/ufs/ufs-mediatek.c >> +++ b/drivers/scsi/ufs/ufs-mediatek.c >> @@ -841,27 +841,27 @@ 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_device_reset(struct ufs_hba *hba, bool asserted) >> { >> struct arm_smccc_res res; >> >> - ufs_mtk_device_reset_ctrl(0, res); >> + if (asserted) { >> + 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); >> + /* >> + * 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); > > I see no point in allowing vendors to "tweak" the 1us->10us adjustment. > The specification says 1us and we all agree that 10us gives us good > enough slack. I.e. this is common code.
Hi Bjron,
We tried, but Samsung fellows wanted 5us. We couldn't get a agreement on this delay in short term, so we chose to leave it in vops.
> >> + } 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); > > The comment in both the Qualcomm and Mediatek drivers claim that this > is > sleep relates to the UFS device (not host), so why should it be > different? > > What happens if I take the device that Mediatek see a need for a 10ms > delay and hook that up to a Qualcomm host? This really should go in the > common code. >
Agree, but Qualcomm host didn't have any problems with 10us yet, so if we put the 10ms delay to common code, Qualcomm host would suffer longer delay when device reset happens - both bootup and resume(xpm_lvl = 5/6) latency would be increased.
Regards, Can Guo.
> > > As such I really would prefer to see these delays in the common code! > You really shouldn't write code based on a speculation that one day > there might come someone who need other values - when that day come we > can just change the code, and if it never comes we're better off with > the cleaner implementation. > > Regards, > Bjorn > >> + } >> >> return 0; >> } >> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c >> index 2206b1e..fed10e5 100644 >> --- a/drivers/scsi/ufs/ufs-qcom.c >> +++ b/drivers/scsi/ufs/ufs-qcom.c >> @@ -1406,10 +1406,11 @@ static void ufs_qcom_dump_dbg_regs(struct >> ufs_hba *hba) >> /** >> * ufs_qcom_device_reset() - toggle the (optional) device reset line >> * @hba: per-adapter instance >> + * @asserted: assert or deassert 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_device_reset(struct ufs_hba *hba, bool asserted) >> { >> struct ufs_qcom_host *host = ufshcd_get_variant(hba); >> >> @@ -1417,15 +1418,20 @@ 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); >> + if (asserted) { >> + gpiod_set_value_cansleep(host->device_reset, 1); >> >> - gpiod_set_value_cansleep(host->device_reset, 0); >> - usleep_range(10, 15); >> + /* >> + * The UFS device shall detect reset pulses of 1us, sleep for 10us >> to >> + * be on the safe side. >> + */ >> + usleep_range(10, 15); >> + } else { >> + gpiod_set_value_cansleep(host->device_reset, 0); >> + >> + /* Some devices may need time to respond to rst_n */ >> + usleep_range(10, 15); >> + } >> >> return 0; >> } >> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c >> index e221add..f2daac2 100644 >> --- a/drivers/scsi/ufs/ufshcd.c >> +++ b/drivers/scsi/ufs/ufshcd.c >> @@ -585,7 +585,13 @@ static void ufshcd_device_reset(struct ufs_hba >> *hba) >> { >> int err; >> >> - err = ufshcd_vops_device_reset(hba); >> + err = ufshcd_vops_device_reset(hba, true); >> + if (err) { >> + dev_err(hba->dev, "asserting device reset failed: %d\n", err); >> + return; >> + } >> + >> + err = ufshcd_vops_device_reset(hba, false); >> >> if (!err) { >> ufshcd_set_ufs_dev_active(hba); >> @@ -593,7 +599,11 @@ static void ufshcd_device_reset(struct ufs_hba >> *hba) >> hba->wb_enabled = false; >> hba->wb_buf_flush_enabled = false; >> } >> + dev_dbg(hba->dev, "device reset done\n"); >> + } else { >> + dev_err(hba->dev, "deasserting device reset failed: %d\n", err); >> } >> + >> if (err != -EOPNOTSUPP) >> ufshcd_update_evt_hist(hba, UFS_EVT_DEV_RESET, err); >> } >> @@ -8686,8 +8696,6 @@ 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 +8711,9 @@ 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_device_reset(hba, true); >> + >> ufshcd_setup_clocks(hba, false); >> >> if (ufshcd_is_clkgating_allowed(hba)) { >> @@ -8711,6 +8722,8 @@ 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 +8791,19 @@ 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 +8811,7 @@ 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 +8878,6 @@ 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 +8888,8 @@ 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..d5fbaba 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 >> + * @device_reset: called to assert or deassert device reset line >> * @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 (*device_reset)(struct ufs_hba *hba, bool asserted); >> 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_device_reset(struct ufs_hba *hba, bool >> asserted) >> { >> if (hba->vops && hba->vops->device_reset) >> - return hba->vops->device_reset(hba); >> + return hba->vops->device_reset(hba, asserted); >> >> return -EOPNOTSUPP; >> } >> -- >> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora >> Forum, >> a Linux Foundation Collaborative Project >>
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