lkml.org 
[lkml]   [2020]   [Feb]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v7 7/8] scsi: ufs-qcom: Delay specific time before gate ref clk
Date
After enter hibern8, as UFS JEDEC ver 3.0 requires, a specific gating wait
time is required before disable the device reference clock. If it is not
specified, use the old delay.

Signed-off-by: Can Guo <cang@codeaurora.org>
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Reviewed-by: Hongwu Su <hongwus@codeaurora.org>
---
drivers/scsi/ufs/ufs-qcom.c | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index 85d7c17..39eefa4 100644
--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c
@@ -833,6 +833,8 @@ static int ufs_qcom_bus_register(struct ufs_qcom_host *host)

static void ufs_qcom_dev_ref_clk_ctrl(struct ufs_qcom_host *host, bool enable)
{
+ unsigned long gating_wait;
+
if (host->dev_ref_clk_ctrl_mmio &&
(enable ^ host->is_dev_ref_clk_enabled)) {
u32 temp = readl_relaxed(host->dev_ref_clk_ctrl_mmio);
@@ -845,11 +847,25 @@ static void ufs_qcom_dev_ref_clk_ctrl(struct ufs_qcom_host *host, bool enable)
/*
* If we are here to disable this clock it might be immediately
* after entering into hibern8 in which case we need to make
- * sure that device ref_clk is active at least 1us after the
+ * sure that device ref_clk is active for specific time after
* hibern8 enter.
*/
- if (!enable)
- udelay(1);
+ if (!enable) {
+ gating_wait = host->hba->dev_info.clk_gating_wait_us;
+ if (!gating_wait) {
+ udelay(1);
+ } else {
+ /*
+ * bRefClkGatingWaitTime defines the minimum
+ * time for which the reference clock is
+ * required by device during transition from
+ * HS-MODE to LS-MODE or HIBERN8 state. Give it
+ * more time to be on the safe side.
+ */
+ gating_wait += 10;
+ usleep_range(gating_wait, gating_wait + 10);
+ }
+ }

writel_relaxed(temp, host->dev_ref_clk_ctrl_mmio);

--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
\
 
 \ /
  Last update: 2020-02-06 09:34    [W:0.076 / U:0.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site