linux-kernel - [PATCH 5/8] scsi: ufs: core: Enable multi-level gear scaling

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Message-Id: <20250116091150.1167739-6-quic_ziqichen@quicinc.com>
Date: Thu, 16 Jan 2025 17:11:46 +0800
From: Ziqi Chen <quic_ziqichen@...cinc.com>
To: quic_cang@...cinc.com, bvanassche@....org, mani@...nel.org,
        beanhuo@...ron.com, avri.altman@....com, junwoo80.lee@...sung.com,
        martin.petersen@...cle.com, quic_ziqichen@...cinc.com,
        quic_nguyenb@...cinc.com, quic_nitirawa@...cinc.com,
        quic_rampraka@...cinc.com
Cc: linux-scsi@...r.kernel.org, Alim Akhtar <alim.akhtar@...sung.com>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Peter Wang <peter.wang@...iatek.com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Andrew Halaney <ahalaney@...hat.com>,
        Maramaina Naresh <quic_mnaresh@...cinc.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 5/8] scsi: ufs: core: Enable multi-level gear scaling

From: Can Guo <quic_cang@...cinc.com>

With OPP V2 enabled, devfreq can scale clocks amongst multiple frequency
plans. However, the gear speed is only toggled between min and max during
clock scaling. Enable multi-level gear scaling by mapping clock frequencies
to gear speeds, so that when devfreq scales clock frequencies we can put
the UFS link at the appropraite gear speeds accordingly.

Co-developed-by: Ziqi Chen <quic_ziqichen@...cinc.com>
Signed-off-by: Ziqi Chen <quic_ziqichen@...cinc.com>
Signed-off-by: Can Guo <quic_cang@...cinc.com>
---
 drivers/ufs/core/ufshcd.c | 46 ++++++++++++++++++++++++++++++---------
 1 file changed, 36 insertions(+), 10 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 8d295cc827cc..839bc23aeda0 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -1308,16 +1308,28 @@ static int ufshcd_wait_for_doorbell_clr(struct ufs_hba *hba,
 /**
  * ufshcd_scale_gear - scale up/down UFS gear
  * @hba: per adapter instance
+ * @target_gear: target gear to scale to
  * @scale_up: True for scaling up gear and false for scaling down
  *
  * Return: 0 for success; -EBUSY if scaling can't happen at this time;
  * non-zero for any other errors.
  */
-static int ufshcd_scale_gear(struct ufs_hba *hba, bool scale_up)
+static int ufshcd_scale_gear(struct ufs_hba *hba, u32 target_gear, bool scale_up)
 {
 	int ret = 0;
 	struct ufs_pa_layer_attr new_pwr_info;
 
+	if (target_gear) {
+		memcpy(&new_pwr_info, &hba->pwr_info,
+		       sizeof(struct ufs_pa_layer_attr));
+
+		new_pwr_info.gear_tx = target_gear;
+		new_pwr_info.gear_rx = target_gear;
+
+		goto do_pmc;
+	}
+
+	/* Legacy gear scaling, in case vops_freq_to_gear_speed() is not implemented */
 	if (scale_up) {
 		memcpy(&new_pwr_info, &hba->clk_scaling.saved_pwr_info,
 		       sizeof(struct ufs_pa_layer_attr));
@@ -1338,6 +1350,7 @@ static int ufshcd_scale_gear(struct ufs_hba *hba, bool scale_up)
 		}
 	}
 
+do_pmc:
 	/* check if the power mode needs to be changed or not? */
 	ret = ufshcd_config_pwr_mode(hba, &new_pwr_info);
 	if (ret)
@@ -1408,15 +1421,19 @@ static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, int err, bool sc
 static int ufshcd_devfreq_scale(struct ufs_hba *hba, unsigned long freq,
 				bool scale_up)
 {
+	u32 old_gear = hba->pwr_info.gear_rx;
+	u32 new_gear = 0;
 	int ret = 0;
 
+	ufshcd_vops_freq_to_gear_speed(hba, freq, &new_gear);
+
 	ret = ufshcd_clock_scaling_prepare(hba, 1 * USEC_PER_SEC);
 	if (ret)
 		return ret;
 
 	/* scale down the gear before scaling down clocks */
 	if (!scale_up) {
-		ret = ufshcd_scale_gear(hba, false);
+		ret = ufshcd_scale_gear(hba, new_gear, false);
 		if (ret)
 			goto out_unprepare;
 	}
@@ -1424,13 +1441,13 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, unsigned long freq,
 	ret = ufshcd_scale_clks(hba, freq, scale_up);
 	if (ret) {
 		if (!scale_up)
-			ufshcd_scale_gear(hba, true);
+			ufshcd_scale_gear(hba, old_gear, true);
 		goto out_unprepare;
 	}
 
 	/* scale up the gear after scaling up clocks */
 	if (scale_up) {
-		ret = ufshcd_scale_gear(hba, true);
+		ret = ufshcd_scale_gear(hba, new_gear, true);
 		if (ret) {
 			ufshcd_scale_clks(hba, hba->devfreq->previous_freq,
 					  false);
@@ -1723,6 +1740,8 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t count)
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
+	struct ufs_clk_info *clki;
+	unsigned long freq;
 	u32 value;
 	int err = 0;
 
@@ -1746,14 +1765,21 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
 
 	if (value) {
 		ufshcd_resume_clkscaling(hba);
-	} else {
-		ufshcd_suspend_clkscaling(hba);
-		err = ufshcd_devfreq_scale(hba, ULONG_MAX, true);
-		if (err)
-			dev_err(hba->dev, "%s: failed to scale clocks up %d\n",
-					__func__, err);
+		goto out_rel;
 	}
 
+	clki = list_first_entry(&hba->clk_list_head, struct ufs_clk_info, list);
+	freq = clki->max_freq;
+
+	ufshcd_suspend_clkscaling(hba);
+	err = ufshcd_devfreq_scale(hba, freq, true);
+	if (err)
+		dev_err(hba->dev, "%s: failed to scale clocks up %d\n",
+				__func__, err);
+	else
+		hba->clk_scaling.target_freq = freq;
+
+out_rel:
 	ufshcd_release(hba);
 	ufshcd_rpm_put_sync(hba);
 out:
-- 
2.34.1