-----Original Message-----
From: Clark Wang <xiaoning.wang@nxp.com>
Sent: Friday, March 19, 2021 14:16
To: Aisheng Dong <aisheng.dong@nxp.com>; shawnguo@kernel.org;
s.hauer@pengutronix.de
Cc: kernel@pengutronix.de; festevam@gmail.com; dl-linux-imx <linux-
imx@nxp.com>; sumit.semwal@linaro.org; christian.koenig@amd.com;
linux-i2c@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
kernel@vger.kernel.org
Subject: RE: [PATCH 02/11] i2c: imx-lpi2c: add runtime pm support

quoted

-----Original Message-----
From: Aisheng Dong <aisheng.dong@nxp.com>
Sent: Friday, March 19, 2021 12:40
To: Clark Wang <xiaoning.wang@nxp.com>; shawnguo@kernel.org;
s.hauer@pengutronix.de
Cc: kernel@pengutronix.de; festevam@gmail.com; dl-linux-imx <linux-
imx@nxp.com>; sumit.semwal@linaro.org; christian.koenig@amd.com;
linux-i2c@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
kernel@vger.kernel.org
Subject: RE: [PATCH 02/11] i2c: imx-lpi2c: add runtime pm support

quoted

From: Clark Wang <xiaoning.wang@nxp.com>
Sent: Wednesday, March 17, 2021 2:54 PM
Subject: [PATCH 02/11] i2c: imx-lpi2c: add runtime pm support

- Add runtime pm support to dynamicly manage the clock.
- Put the suspend to suspend_noirq.
- Call .pm_runtime_force_suspend() to force runtime pm suspended
  in .suspend_noirq().

The patch title needs to be improved as the driver already supports rpm.
And do one thing in one patch.

quoted

Signed-off-by: Fugang Duan <redacted>
Signed-off-by: Gao Pan <redacted>
Reviewed-by: Anson Huang <redacted>

Please add your sign-off.

quoted

---
 drivers/i2c/busses/i2c-imx-lpi2c.c | 50
++++++++++++++++++++----------
 1 file changed, 33 insertions(+), 17 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c

b/drivers/i2c/busses/i2c-imx-lpi2c.c
index bbf44ac95021..1e920e7ac7c1 100644

--- a/drivers/i2c/busses/i2c-imx-lpi2c.c
+++ b/drivers/i2c/busses/i2c-imx-lpi2c.c

@@ -574,7 +574,8 @@ static int lpi2c_imx_probe(struct platform_device

*pdev)
 	if (ret)
 		lpi2c_imx->bitrate = I2C_MAX_STANDARD_MODE_FREQ;

-	ret = devm_request_irq(&pdev->dev, irq, lpi2c_imx_isr, 0,
+	ret = devm_request_irq(&pdev->dev, irq, lpi2c_imx_isr,
+			       IRQF_NO_SUSPEND,

This belongs to a separate patch

quoted

 			       pdev->name, lpi2c_imx);
 	if (ret) {
 		dev_err(&pdev->dev, "can't claim irq %d\n", irq); @@ -

584,35

quoted

+585,32 @@ static int lpi2c_imx_probe(struct platform_device *pdev)
 	i2c_set_adapdata(&lpi2c_imx->adapter, lpi2c_imx);
 	platform_set_drvdata(pdev, lpi2c_imx);

-	ret = clk_prepare_enable(lpi2c_imx->clk);
-	if (ret) {
-		dev_err(&pdev->dev, "clk enable failed %d\n", ret);
-		return ret;
-	}
-
 	pm_runtime_set_autosuspend_delay(&pdev->dev,

I2C_PM_TIMEOUT);

quoted

 	pm_runtime_use_autosuspend(&pdev->dev);
-	pm_runtime_get_noresume(&pdev->dev);
-	pm_runtime_set_active(&pdev->dev);
 	pm_runtime_enable(&pdev->dev);

+	ret = pm_runtime_get_sync(&pdev->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(&pdev->dev);
+		dev_err(&pdev->dev, "failed to enable clock\n");
+		return ret;
+	}

Can't current clk control via rpm work well?
Please describe why need change.

I think the previous patch maker might want to use the return value of
pm_runtime_get_sync to check whether the clock has been turned on
correctly to
avoid the kernel panic.
Maybe I can change to the method like this.
	pm_runtime_get_noresume(&pdev->dev);
	ret = pm_runtime_set_active(&pdev->dev);
	if (ret < 0)
		goto out;
	pm_runtime_enable(&pdev->dev);

Best Regards,
Clark Wang

Sorry, I missed the point before.
If we use pm_runtime_get_noresume(&pdev->dev); and 
pm_runtime_set_active(&pdev->dev); here, the clk should be enabled by using 
clk_prepare_enable() in the probe function. However, the call of 
clk_prepare_enable() is already in lpi2c_runtime_resume().
Using get_sync() here can help to reduce the repetitive code, especially ipg 
clk will be added later.
Shall we change to use pm_runtime_get_sync() here?

Regards,
Clark Wang