[PATCH v1 1/2] scsi: ufs: add required delay after gating reference clock
From: Stanley Chu <hidden>
Date: 2020-02-17 09:36:10
Also in:
linux-arm-kernel, linux-scsi, lkml
Subsystem:
scsi subsystem, the rest · Maintainers:
"James E.J. Bottomley", "Martin K. Petersen", Linus Torvalds
In UFS version 3.0, a newly added attribute bRefClkGatingWaitTime defines the minimum time for which the reference clock is required by device during transition to LS-MODE or HIBERN8 state. Currently this time is detected and stored in hba->dev_info.clk_gating_wait_us but applied to vendor implementatios only. Make it applied to reference clock named as "ref_clk" in device tree in common path. Signed-off-by: Stanley Chu <redacted> --- drivers/scsi/ufs/ufshcd.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 744b8254220c..7f60721f54d1 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c@@ -7417,8 +7417,10 @@ static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on, struct ufs_clk_info *clki; struct list_head *head = &hba->clk_list_head; unsigned long flags; + unsigned long wait_us; ktime_t start = ktime_get(); bool clk_state_changed = false; + bool ref_clk; if (list_empty(head)) goto out;
@@ -7436,7 +7438,8 @@ static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on, list_for_each_entry(clki, head, list) { if (!IS_ERR_OR_NULL(clki->clk)) { - if (skip_ref_clk && !strcmp(clki->name, "ref_clk")) + ref_clk = !strcmp(clki->name, "ref_clk") ? true : false; + if (skip_ref_clk && ref_clk) continue; clk_state_changed = on ^ clki->enabled;
@@ -7449,6 +7452,9 @@ static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on, } } else if (!on && clki->enabled) { clk_disable_unprepare(clki->clk); + wait_us = hba->dev_info.clk_gating_wait_us; + if (ref_clk && wait_us) + usleep_range(wait_us, wait_us + 10); } clki->enabled = on; dev_dbg(hba->dev, "%s: clk: %s %sabled\n", __func__,
--
2.18.0
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