linux-kernel - [PATCH 1/2] scsi: ufs: Suspend clk scaling on no request

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Date: Wed, 26 Jun 2024 16:00:32 +0530
From: Ram Prakash Gupta <quic_rampraka@...cinc.com>
To: "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Alim Akhtar <alim.akhtar@...sung.com>, Avri Altman <avri.altman@....com>,
        Bart Van Assche <bvanassche@....org>, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        quic_cang@...cinc.com, quic_nguyenb@...cinc.com,
        quic_rampraka@...cinc.com, quic_pragalla@...cinc.com,
        quic_nitirawa@...cinc.com
Subject: [PATCH 1/2] scsi: ufs: Suspend clk scaling on no request

Currently ufs clk scaling is getting suspended only when the
clks are scaled down, but next when high load is generated its
adding a huge amount of latency in scaling up the clk and complete
the request post that.

Now if the scaling is suspended in its existing state, and when high
load is generated it is helping improve the random performance KPI by
28%. So suspending the scaling when there is no request. And the clk
would be put in low scaled state when the actual request load is low.

Making this change as optional for other vendor by having the check
enabled using vops as for some vendor suspending without bringing the
clk in low scaled state might have impact on power consumption on the
SoC.

Signed-off-by: Ram Prakash Gupta <quic_rampraka@...cinc.com>
---
 drivers/ufs/core/ufshcd.c | 3 ++-
 include/ufs/ufshcd.h      | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 1b65e6ae4137..0dc9928ae18d 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -1560,7 +1560,8 @@ static int ufshcd_devfreq_target(struct device *dev,
 		ktime_to_us(ktime_sub(ktime_get(), start)), ret);
 
 out:
-	if (sched_clk_scaling_suspend_work && !scale_up)
+	if (sched_clk_scaling_suspend_work && (!scale_up ||
+				hba->clk_scaling.suspend_on_no_request))
 		queue_work(hba->clk_scaling.workq,
 			   &hba->clk_scaling.suspend_work);
 
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index bad88bd91995..c14607f2890b 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -457,6 +457,7 @@ struct ufs_clk_scaling {
 	bool is_initialized;
 	bool is_busy_started;
 	bool is_suspended;
+	bool suspend_on_no_request;
 };
 
 #define UFS_EVENT_HIST_LENGTH 8
-- 
2.17.1