The ufshcd_wait_for_register() function either sleeps or spins until the
specified register has reached the desired value. Busy-waiting is not
only considered a bad practice but also has a bad impact on energy
consumption. Always sleep instead of spinning by making sure that all
ufshcd_wait_for_register() calls happen from a context where it is
allowed to sleep. The only function call that has to be moved is the
ufshcd_hba_stop() call in ufshcd_host_reset_and_restore().
Cc: Can Guo <cang@xxxxxxxxxxxxxx>
Cc: Avri Altman <avri.altman@xxxxxxx>
Cc: Bean Huo <beanhuo@xxxxxxxxxx>
Cc: Alim Akhtar <alim.akhtar@xxxxxxxxxxx>
Cc: Asutosh Das <asutoshd@xxxxxxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
drivers/scsi/ufs/ufshcd.c | 51 +++++++++++++++++++++------------------
drivers/scsi/ufs/ufshcd.h | 2 +-
2 files changed, 29 insertions(+), 24 deletions(-)
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index bf7caea2253b..72069d4faa1e 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -563,21 +563,21 @@ void ufshcd_delay_us(unsigned long us, unsigned long tolerance)
}
EXPORT_SYMBOL_GPL(ufshcd_delay_us);
-/*
+/**
* ufshcd_wait_for_register - wait for register value to change
- * @hba - per-adapter interface
- * @reg - mmio register offset
- * @mask - mask to apply to read register value
- * @val - wait condition
- * @interval_us - polling interval in microsecs
- * @timeout_ms - timeout in millisecs
- * @can_sleep - perform sleep or just spin
+ * @hba: per-adapter interface
+ * @reg: mmio register offset
+ * @mask: mask to apply to the read register value
+ * @val: value to wait for
+ * @interval_us: polling interval in microseconds
+ * @timeout_ms: timeout in milliseconds
*
- * Returns -ETIMEDOUT on error, zero on success
+ * Return:
+ * -ETIMEDOUT on error, zero on success.
*/
int ufshcd_wait_for_register(struct ufs_hba *hba, u32 reg, u32 mask,
u32 val, unsigned long interval_us,
- unsigned long timeout_ms, bool can_sleep)
+ unsigned long timeout_ms)
{
int err = 0;
unsigned long timeout = jiffies + msecs_to_jiffies(timeout_ms);
@@ -586,10 +586,7 @@ int ufshcd_wait_for_register(struct ufs_hba *hba, u32 reg, u32 mask,
val = val & mask;
while ((ufshcd_readl(hba, reg) & mask) != val) {
- if (can_sleep)
- usleep_range(interval_us, interval_us + 50);
- else
- udelay(interval_us);
+ usleep_range(interval_us, interval_us + 50);
if (time_after(jiffies, timeout)) {
if ((ufshcd_readl(hba, reg) & mask) != val)
err = -ETIMEDOUT;
@@ -2589,7 +2586,7 @@ ufshcd_clear_cmd(struct ufs_hba *hba, int tag)
*/
err = ufshcd_wait_for_register(hba,
REG_UTP_TRANSFER_REQ_DOOR_BELL,
- mask, ~mask, 1000, 1000, true);
+ mask, ~mask, 1000, 1000);
return err;
}
@@ -4258,16 +4255,23 @@ EXPORT_SYMBOL_GPL(ufshcd_make_hba_operational);
/**
* ufshcd_hba_stop - Send controller to reset state
* @hba: per adapter instance
- * @can_sleep: perform sleep or just spin
*/
-static inline void ufshcd_hba_stop(struct ufs_hba *hba, bool can_sleep)
+static inline void ufshcd_hba_stop(struct ufs_hba *hba)
{
+ unsigned long flags;
int err;
+ /*
+ * Obtain the host lock to prevent that the controller is disabled
+ * while the UFS interrupt handler is active on another CPU.
+ */
+ spin_lock_irqsave(hba->host->host_lock, flags);
ufshcd_writel(hba, CONTROLLER_DISABLE, REG_CONTROLLER_ENABLE);
+ spin_unlock_irqrestore(hba->host->host_lock, flags);
+
err = ufshcd_wait_for_register(hba, REG_CONTROLLER_ENABLE,
CONTROLLER_ENABLE, CONTROLLER_DISABLE,
- 10, 1, can_sleep);
+ 10, 1);
if (err)
dev_err(hba->dev, "%s: Controller disable failed\n", __func__);
}
@@ -4288,7 +4292,7 @@ int ufshcd_hba_enable(struct ufs_hba *hba)
if (!ufshcd_is_hba_active(hba))
/* change controller state to "reset state" */
- ufshcd_hba_stop(hba, true);
+ ufshcd_hba_stop(hba);
/* UniPro link is disabled at this point */
ufshcd_set_link_off(hba);
@@ -5911,7 +5915,7 @@ static int ufshcd_clear_tm_cmd(struct ufs_hba *hba, int tag)
/* poll for max. 1 sec to clear door bell register by h/w */
err = ufshcd_wait_for_register(hba,
REG_UTP_TASK_REQ_DOOR_BELL,
- mask, 0, 1000, 1000, true);
+ mask, 0, 1000, 1000);
out:
return err;
}
@@ -6478,8 +6482,9 @@ static int ufshcd_host_reset_and_restore(struct ufs_hba *hba)
* Stop the host controller and complete the requests
* cleared by h/w
*/
+ ufshcd_hba_stop(hba);
+
spin_lock_irqsave(hba->host->host_lock, flags);
- ufshcd_hba_stop(hba, false);
hba->silence_err_logs = true;
ufshcd_complete_requests(hba);
hba->silence_err_logs = false;
@@ -7986,7 +7991,7 @@ static int ufshcd_link_state_transition(struct ufs_hba *hba,
* Change controller state to "reset state" which
* should also put the link in off/reset state
*/
- ufshcd_hba_stop(hba, true);
+ ufshcd_hba_stop(hba);
/*
* TODO: Check if we need any delay to make sure that
* controller is reset
@@ -8545,7 +8550,7 @@ void ufshcd_remove(struct ufs_hba *hba)
scsi_remove_host(hba->host);
/* disable interrupts */
ufshcd_disable_intr(hba, hba->intr_mask);
- ufshcd_hba_stop(hba, true);
+ ufshcd_hba_stop(hba);
ufshcd_exit_clk_scaling(hba);
ufshcd_exit_clk_gating(hba);
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 733722840794..5c944530cde5 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -822,7 +822,7 @@ int ufshcd_uic_hibern8_exit(struct ufs_hba *hba);
void ufshcd_delay_us(unsigned long us, unsigned long tolerance);
int ufshcd_wait_for_register(struct ufs_hba *hba, u32 reg, u32 mask,
u32 val, unsigned long interval_us,
- unsigned long timeout_ms, bool can_sleep);
+ unsigned long timeout_ms);
void ufshcd_parse_dev_ref_clk_freq(struct ufs_hba *hba, struct clk *refclk);
void ufshcd_update_reg_hist(struct ufs_err_reg_hist *reg_hist,
u32 reg);
