[PATCH AUTOSEL 6.17] scsi: ufs: ufs-qcom: Disable lane clocks during phy hibern8

[Sasha Levin <sashal@kernel.org>]

From: Palash Kambar <quic_pkambar@quicinc.com>

[ Upstream commit c1553fc105dff28f79bef90fab207235f5f2d977 ]

Currently, the UFS lane clocks remain enabled even after the link enters
the Hibern8 state and are only disabled during runtime/system
suspend.This patch modifies the behavior to disable the lane clocks
during ufs_qcom_setup_clocks(), which is invoked shortly after the link
enters Hibern8 via gate work.

While hibern8_notify() offers immediate control, toggling clocks on
every transition isn't ideal due to varied contexts like clock scaling.
Since setup_clocks() manages PHY/controller resources and is invoked
soon after Hibern8 entry, it serves as a central and stable point for
clock gating.

Signed-off-by: Palash Kambar <quic_pkambar@quicinc.com>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Message-ID: <20250909055149.2068737-1-quic_pkambar@quicinc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

YES – the change fixes a real power-management bug with minimal, well-
scoped risk.

- `drivers/ufs/host/ufs-qcom.c:1226` now shuts the lane clocks off when
  `ufshcd_setup_clocks(hba, false)` runs while the link is in Hibern8.
  Without this, the lane clocks stayed on after the gate work forced
  Hibern8 (see `drivers/ufs/core/ufshcd.c:2038-2054`), so clock gating
  never delivered the expected idle power savings—lane clocks previously
  only dropped during the much rarer runtime/system suspend path
  (`drivers/ufs/host/ufs-qcom.c:739`).
- `drivers/ufs/host/ufs-qcom.c:1192-1200` symmetrically re-enable the
  lane clocks before the controller leaves Hibern8, so existing
  resume/ungate flows remain intact. The helper already handles errors
  in the same way other call sites (e.g., resume) do, so the added
  `dev_err(...)` path doesn’t introduce new behavior beyond propagating
  a genuine enabling failure.
- The patch touches only the Qualcomm variant, relies on helpers already
  present in stable branches (older trees use the per-lane helpers but
  the hook points are identical), and doesn’t alter any interfaces or
  broader subsystem behavior. Backporting just requires adding the same
  on/off checks in the older `ufs_qcom_setup_clocks()` body.

Given that it restores the intended low-power behavior for idle gating
on Qualcomm UFS hosts and stays tightly contained, it’s a good candidate
for stable. Suggested follow-up after backport: exercise runtime PM or
idle-gating tests to confirm the link enters/leaves Hibern8 cleanly.

 drivers/ufs/host/ufs-qcom.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
index 3ea6b08d2b526..2b6eb377eec07 100644
--- a/drivers/ufs/host/ufs-qcom.c
+++ b/drivers/ufs/host/ufs-qcom.c
@@ -1183,6 +1183,13 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
 	case PRE_CHANGE:
 		if (on) {
 			ufs_qcom_icc_update_bw(host);
+			if (ufs_qcom_is_link_hibern8(hba)) {
+				err = ufs_qcom_enable_lane_clks(host);
+				if (err) {
+					dev_err(hba->dev, "enable lane clks failed, ret=%d\n", err);
+					return err;
+				}
+			}
 		} else {
 			if (!ufs_qcom_is_link_active(hba)) {
 				/* disable device ref_clk */
@@ -1208,6 +1215,9 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
 			if (ufshcd_is_hs_mode(&hba->pwr_info))
 				ufs_qcom_dev_ref_clk_ctrl(host, true);
 		} else {
+			if (ufs_qcom_is_link_hibern8(hba))
+				ufs_qcom_disable_lane_clks(host);
+
 			ufs_qcom_icc_set_bw(host, ufs_qcom_bw_table[MODE_MIN][0][0].mem_bw,
 					    ufs_qcom_bw_table[MODE_MIN][0][0].cfg_bw);
 		}
-- 
2.51.0