scsi: ufs-qcom: Delay specific time before gate ref clk
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.
Link: https://lore.kernel.org/r/1581392451-28743-8-git-send-email-cang@codeaurora.org
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Reviewed-by: Hongwu Su <hongwus@codeaurora.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index 2800a47..8339050 100644
--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c
@@ -843,11 +843,27 @@ 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) {
+ unsigned long gating_wait;
+
+ 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 delay 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);