[PATCH RFC v4 1/1] scsi: ufs: Fix ufs power down/on specs violation

Ziqi Chen
2020-12-22T13:51:21Z

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);
+ } 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;
}
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;
}
--
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