Messages in this thread | | | Date | Tue, 29 Dec 2020 09:48:08 +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 09:18, Can Guo wrote: > 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. >
Besides, currently this device reset vops is only registered by ufs-qcom.c and ufs-mediatek.c, meaning any delays that we put in the common code are not necessary for those who do not have this vops registered, i.e ufs-exynos.c, ufs-hisi.c.
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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