linux-kernel - [PATCH V1 2/3] scsi: ufs: pltfrm: Add parsing support for disable LPM property

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Message-ID: <20250417124645.24456-3-quic_nitirawa@quicinc.com>
Date: Thu, 17 Apr 2025 18:16:44 +0530
From: Nitin Rawat <quic_nitirawa@...cinc.com>
To: alim.akhtar@...sung.com, avri.altman@....com, bvanassche@....org,
        krzk+dt@...nel.org, robh@...nel.org, mani@...nel.org,
        conor+dt@...nel.org, James.Bottomley@...senPartnership.com,
        martin.petersen@...cle.com, beanhuo@...ron.com,
        peter.wang@...iatek.com
Cc: linux-arm-msm@...r.kernel.org, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        Nitin Rawat <quic_nitirawa@...cinc.com>
Subject: [PATCH V1 2/3] scsi: ufs: pltfrm: Add parsing support for disable LPM property

There are emulation FPGA platforms or other platforms where UFS low
power mode is either unsupported or power efficiency is not a critical
requirement.

Add support for parsing disable LPM property from device tree . The
disable lpm support in devicetree is added through the "disable-lpm"
property for such platforms.

Disabling LPM ensure stable operation and compatibility with these
environments, where power management features might interfere with
performance or functionality.

Signed-off-by: Nitin Rawat <quic_nitirawa@...cinc.com>
---
 drivers/ufs/host/ufshcd-pltfrm.c | 15 +++++++++++++++
 include/ufs/ufshcd.h             |  1 +
 2 files changed, 16 insertions(+)

diff --git a/drivers/ufs/host/ufshcd-pltfrm.c b/drivers/ufs/host/ufshcd-pltfrm.c
index ffe5d1d2b215..764525d9262b 100644
--- a/drivers/ufs/host/ufshcd-pltfrm.c
+++ b/drivers/ufs/host/ufshcd-pltfrm.c
@@ -210,6 +210,19 @@ static void ufshcd_init_lanes_per_dir(struct ufs_hba *hba)
 	}
 }

+/**
+ * ufshcd_parse_lpm_support - read from DT whether LPM modes should be disabled.
+ * @hba: host controller instance
+ */
+static void ufshcd_parse_lpm_support(struct ufs_hba *hba)
+{
+	struct device *dev = hba->dev;
+
+	hba->disable_lpm = of_property_read_bool(dev->of_node, "disable-lpm");
+	if (hba->disable_lpm)
+		dev_info(hba->dev, "UFS LPM is disabled\n");
+}
+
 /**
  * ufshcd_parse_clock_min_max_freq  - Parse MIN and MAX clocks freq
  * @hba: per adapter instance
@@ -495,6 +508,8 @@ int ufshcd_pltfrm_init(struct platform_device *pdev,

 	ufshcd_init_lanes_per_dir(hba);

+	ufshcd_parse_lpm_support(hba);
+
 	err = ufshcd_parse_operating_points(hba);
 	if (err) {
 		dev_err(dev, "%s: OPP parse failed %d\n", __func__, err);
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index e928ed0265ff..5a3daed1f086 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -1143,6 +1143,7 @@ struct ufs_hba {
 	int critical_health_count;
 	atomic_t dev_lvl_exception_count;
 	u64 dev_lvl_exception_id;
+	bool disable_lpm;
 };

 /**
--
2.48.1