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[104.57.184.186]) by smtp.gmail.com with ESMTPSA id e10sm8507350otr.73.2020.12.28.09.55.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Dec 2020 09:55:07 -0800 (PST) Date: Mon, 28 Dec 2020 11:55:04 -0600 From: Bjorn Andersson To: Ziqi Chen Cc: asutoshd@codeaurora.org, nguyenb@codeaurora.org, cang@codeaurora.org, hongwus@codeaurora.org, rnayak@codeaurora.org, vinholikatti@gmail.com, jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, linux-scsi@vger.kernel.org, kernel-team@android.com, saravanak@google.com, salyzyn@google.com, kwmad.kim@samsung.com, stanley.chu@mediatek.com, Alim Akhtar , Avri Altman , "James E.J. Bottomley" , Andy Gross , Matthias Brugger , Bean Huo , Bart Van Assche , Adrian Hunter , Satya Tangirala , "moderated list:UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER..." , open list , "open list:ARM/QUALCOMM SUPPORT" , "moderated list:ARM/Mediatek SoC support" Subject: Re: [PATCH RFC v4 1/1] scsi: ufs: Fix ufs power down/on specs violation Message-ID: References: <1608644981-46267-1-git-send-email-ziqichen@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1608644981-46267-1-git-send-email-ziqichen@codeaurora.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > Cc: Stanley Chu > Signed-off-by: Ziqi Chen > --- > 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. > + } 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. 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 >