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scsi: ufs: Make ufshcd_wait_for_register() sleep instead of busy-waiting

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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().

Link: https://lore.kernel.org/r/20200507222750.19113-1-bvanassche@acm.org
Cc: Can Guo <cang@codeaurora.org>
Cc: Avri Altman <avri.altman@wdc.com>
Cc: Bean Huo <beanhuo@micron.com>
Cc: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Asutosh Das <asutoshd@codeaurora.org>
Tested-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Bart Van Assche 2020-05-07 15:27:50 -07:00 committed by Martin K. Petersen
parent d0b1e4a638
commit 5cac1095cf
2 changed files with 29 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
drivers/scsi/ufs/ufshcd.c
View File

@ -562,21 +562,21 @@ 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);
@ -585,10 +585,7 @@ 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;
@ -2577,7 +2574,7 @@ 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;
}
@ -4247,16 +4244,23 @@ 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__);
}
@ -4277,7 +4281,7 @@ 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);
@ -5906,7 +5910,7 @@ 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;
}
@ -6482,8 +6486,9 @@ 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;
@ -8049,7 +8054,7 @@ 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
@ -8608,7 +8613,7 @@ 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);

2
drivers/scsi/ufs/ufshcd.h
View File

@ -831,7 +831,7 @@ 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);