Re: [PATCH v4 7/8] scsi: ufs-qcom: Delay specific time before gate ref clk

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On 1/22/2020 11:25 PM, Can Guo wrote:
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@xxxxxxxxxxxxxx>
---

Reviewed-by: Asutosh Das <asutoshd@xxxxxxxxxxxxxx>

  drivers/scsi/ufs/ufs-qcom.c | 13 ++++++++++---
  1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index 85d7c17..3b5b2d9 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 +847,16 @@ 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
+				usleep_range(gating_wait, gating_wait + 10);
+		}
writel_relaxed(temp, host->dev_ref_clk_ctrl_mmio);


--
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