-----Original Message-----
From: Vinod Koul <vkoul@kernel.org>
Sent: Tuesday, September 20, 2022 5:20 PM
To: Mehta, Piyush <redacted>
Cc: laurent.pinchart@ideasonboard.com; kishon@ti.com;
michal.simek@xilinx.com; Simek, Michal [off-list ref]; linux-
kernel@vger.kernel.org; linux-phy@lists.infradead.org; linux-arm-
kernel@lists.infradead.org; git (AMD-Xilinx) [off-list ref]; Paladugu, Siva
Durga Prasad [off-list ref]
Subject: Re: [PATCH] phy: xilinx: phy-zynqmp: dynamic clock support for
power-save

On 20-09-22, 10:38, Mehta, Piyush wrote:

quoted

Hello @Vinod Koul,

Thanks for review comments.
Please find my inline comments below with tag [Piyush].

Please _do_ _not_ _top_ _post_

And learn how to reply upstream. Am sure there at people at AMD/Xilinx
who know this..

quoted

Regards,
Piyush Mehta

quoted

-----Original Message-----
From: Vinod Koul <vkoul@kernel.org>
Sent: Tuesday, September 20, 2022 12:11 PM
To: Mehta, Piyush <redacted>
Cc: laurent.pinchart@ideasonboard.com; kishon@ti.com;
michal.simek@xilinx.com; Simek, Michal [off-list ref];
linux- kernel@vger.kernel.org; linux-phy@lists.infradead.org;
linux-arm- kernel@lists.infradead.org; git (AMD-Xilinx)
[off-list ref]; Paladugu, Siva Durga Prasad
[off-list ref]
Subject: Re: [PATCH] phy: xilinx: phy-zynqmp: dynamic clock support
for power-save

On 09-09-22, 18:34, Piyush Mehta wrote:

quoted

Enabling clock for all the lanes, consuming power even PHY is
active or not.

Pls consider revision to:
Enabling clock for all the lanes consumes power even PHY is active or

idle..

quoted

[Piyush]:  will address in next version of patch.

quoted

quoted

To resolve the above issue and power saving,made clock
enabled/disabled based on active PHYs on call of phy_init/phy_exit.

To resolve this, enable/disable clocks in phy_init/phy_exit

[Piyush]:  will address in next version of patch.

quoted

quoted

By default clock is disabled for all the lanes. Whenever phy_init
called from USB, SATA, SGMII, or display driver, it enabled the
required clock for requested lane. On phy_exit cycle, it disabled
clock for the active PHYs.

During the suspend/resume cycle, each USB/ SATA/ SGMII/ display
driver called phy_exit/phy_init individually. it disabled clock on
exit, and enabled on initialization for the active PHYs.

Active PHY configuration depends on the peripheral DT node status,
like USB DT node status 'okay' then driver enabled clock for the
USB configured lane.

Signed-off-by: Piyush Mehta <redacted>
---
 drivers/phy/xilinx/phy-zynqmp.c | 59
++++++++-------------------------
 1 file changed, 14 insertions(+), 45 deletions(-)

diff --git a/drivers/phy/xilinx/phy-zynqmp.c

b/drivers/phy/xilinx/phy-zynqmp.c index 9be9535ad7ab..912c4defdf8d
100644

--- a/drivers/phy/xilinx/phy-zynqmp.c
+++ b/drivers/phy/xilinx/phy-zynqmp.c

@@ -572,6 +572,10 @@ static int xpsgtr_phy_init(struct phy *phy)

 	mutex_lock(&gtr_dev->gtr_mutex);

+	/* Configure and enable the clock when peripheral phy_init call
+*/

when peripheral invokes phy_init

quoted

+	if (clk_prepare_enable(gtr_dev->clk[gtr_phy->lane]))
+		goto out;
+
 	/* Skip initialization if not required. */
 	if (!xpsgtr_phy_init_required(gtr_phy))
 		goto out;

@@ -616,9 +620,13 @@ static int xpsgtr_phy_init(struct phy *phy)

static int xpsgtr_phy_exit(struct phy *phy)  {
 	struct xpsgtr_phy *gtr_phy = phy_get_drvdata(phy);
+	struct xpsgtr_dev *gtr_dev = gtr_phy->dev;

 	gtr_phy->skip_phy_init = false;

+	/* Ensure that disable clock only, which configure for lane */
+	clk_disable_unprepare(gtr_dev->clk[gtr_phy->lane]);
+
 	return 0;
 }

@@ -824,15 +832,11 @@ static struct phy *xpsgtr_xlate(struct

device *dev,  static int __maybe_unused xpsgtr_suspend(struct device

*dev)  {

quoted

quoted

quoted

 	struct xpsgtr_dev *gtr_dev = dev_get_drvdata(dev);
-	unsigned int i;

 	/* Save the snapshot ICM_CFG registers. */
 	gtr_dev->saved_icm_cfg0 = xpsgtr_read(gtr_dev, ICM_CFG0);
 	gtr_dev->saved_icm_cfg1 = xpsgtr_read(gtr_dev, ICM_CFG1);

-	for (i = 0; i < ARRAY_SIZE(gtr_dev->clk); i++)
-		clk_disable_unprepare(gtr_dev->clk[i]);
-
 	return 0;
 }

@@ -842,13 +846,6 @@ static int __maybe_unused

xpsgtr_resume(struct

device *dev)

quoted

 	unsigned int icm_cfg0, icm_cfg1;
 	unsigned int i;
 	bool skip_phy_init;
-	int err;
-
-	for (i = 0; i < ARRAY_SIZE(gtr_dev->clk); i++) {
-		err = clk_prepare_enable(gtr_dev->clk[i]);
-		if (err)
-			goto err_clk_put;
-	}

hold on, why is this being removed from suspend/resume?

[Piyush]:
Now, each peripheral driver calls phy_exit/phy_init in suspend/resume,

and respective active driver will do clock enable and disable.

quoted

In above xpsgtr resume calls, by default all the clock enabled for all the

lanes, that consumes power even PHY is active or not.

quoted

So, the clock will be enabled only for active PHY in the phy_init and disabled

in phy_exit. Clock enabling is not required at multiple times.

Learn to use a proper Linux MUA while replying on mail lists

on you comment:
1. leaving clock on all the time does not sound right to me 2. why not enable
pm_runtime for this driver and do better with power

Enable pm_runtime support:

We have a fixed clock for the GT lanes, as earlier explained GT specific clock is enabled on phy
initialization of the active state of peripheral (node status = "Okay"), and disabled on exit.

For pm_runtime design support:

static int __maybe_unused xpsgtr_runtime_suspend(struct device *dev) {
	return 0;
}

static int __maybe_unused xpsgtr_runtime_resume(struct device *dev) {
	return 0;
}

static int __maybe_unused xpsgtr_runtime_idle(struct device *dev) {
	pm_runtime_mark_last_busy(dev);
	pm_runtime_autosuspend(dev);
	return 0;
}

static const struct dev_pm_ops xpsgtr_pm_ops = {
	SET_RUNTIME_PM_OPS(xpsgtr_runtime_suspend,
			   xpsgtr_runtime_resume, xpsgtr_runtime_idle)
 };

We don't enable/disable the clock on suspend/resume calls, so is it acceptable to have empty PM ops (xpsgtr_runtime_suspend / xpsgtr_runtime_resume)?

 3. Changes need to be

documented in changelog, this was not explained in log so unexpected

I will rephrase the commit description to have a detailed description.

quoted

quoted

quoted

 	icm_cfg0 = xpsgtr_read(gtr_dev, ICM_CFG0);
 	icm_cfg1 = xpsgtr_read(gtr_dev, ICM_CFG1); @@ -869,12 +866,6

@@

quoted

static int __maybe_unused xpsgtr_resume(struct device *dev)
 		gtr_dev->phys[i].skip_phy_init = skip_phy_init;

 	return 0;
-
-err_clk_put:
-	while (i--)
-		clk_disable_unprepare(gtr_dev->clk[i]);
-
-	return err;
 }

 static const struct dev_pm_ops xpsgtr_pm_ops = { @@ -888,7 +879,6

@@ static const struct dev_pm_ops xpsgtr_pm_ops = {  static int

xpsgtr_get_ref_clocks(struct xpsgtr_dev *gtr_dev)  {
 	unsigned int refclk;
-	int ret;

 	for (refclk = 0; refclk < ARRAY_SIZE(gtr_dev->refclk_sscs); ++refclk) {
 		unsigned long rate;

@@ -899,19 +889,14 @@ static int xpsgtr_get_ref_clocks(struct

xpsgtr_dev

*gtr_dev)

quoted

 		snprintf(name, sizeof(name), "ref%u", refclk);
 		clk = devm_clk_get_optional(gtr_dev->dev, name);
 		if (IS_ERR(clk)) {
-			ret = dev_err_probe(gtr_dev->dev, PTR_ERR(clk),
-					    "Failed to get reference clock

%u\n",

quoted

-					    refclk);
-			goto err_clk_put;
+			return dev_err_probe(gtr_dev->dev, PTR_ERR(clk),
+					     "Failed to get ref clock %u\n",
+					     refclk);
 		}

 		if (!clk)
 			continue;

-		ret = clk_prepare_enable(clk);
-		if (ret)
-			goto err_clk_put;
-
 		gtr_dev->clk[refclk] = clk;

 		/*

@@ -931,18 +916,11 @@ static int xpsgtr_get_ref_clocks(struct

xpsgtr_dev

*gtr_dev)

quoted

 			dev_err(gtr_dev->dev,
 				"Invalid rate %lu for reference clock %u\n",
 				rate, refclk);
-			ret = -EINVAL;
-			goto err_clk_put;
+			return -EINVAL;
 		}
 	}

 	return 0;
-
-err_clk_put:
-	while (refclk--)
-		clk_disable_unprepare(gtr_dev->clk[refclk]);
-
-	return ret;
 }

 static int xpsgtr_probe(struct platform_device *pdev) @@ -951,7
+929,6 @@ static int xpsgtr_probe(struct platform_device *pdev)
 	struct xpsgtr_dev *gtr_dev;
 	struct phy_provider *provider;
 	unsigned int port;
-	unsigned int i;
 	int ret;

 	gtr_dev = devm_kzalloc(&pdev->dev, sizeof(*gtr_dev),
GFP_KERNEL);

@@

quoted

-991,8 +968,7 @@ static int xpsgtr_probe(struct platform_device

*pdev)

quoted

quoted

quoted

 		phy = devm_phy_create(&pdev->dev, np, &xpsgtr_phyops);
 		if (IS_ERR(phy)) {
 			dev_err(&pdev->dev, "failed to create PHY\n");
-			ret = PTR_ERR(phy);
-			goto err_clk_put;
+			return PTR_ERR(phy);
 		}

 		gtr_phy->phy = phy;

@@ -1003,16 +979,9 @@ static int xpsgtr_probe(struct

platform_device

*pdev)

quoted

 	provider = devm_of_phy_provider_register(&pdev->dev,

xpsgtr_xlate);

quoted

 	if (IS_ERR(provider)) {
 		dev_err(&pdev->dev, "registering provider failed\n");
-		ret = PTR_ERR(provider);
-		goto err_clk_put;
+		return PTR_ERR(provider);
 	}
 	return 0;
-
-err_clk_put:
-	for (i = 0; i < ARRAY_SIZE(gtr_dev->clk); i++)
-		clk_disable_unprepare(gtr_dev->clk[i]);
-
-	return ret;
 }

 static const struct of_device_id xpsgtr_of_match[] = {
--
2.25.1

--
~Vinod

--
~Vinod

Regards,
Piyush Mehta

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