Re: [PATCH v2] fpga: zynq-fpga: Enable pm_runtime (suspend, resume)

From: Mike Looijmans
Date: Tue Nov 24 2015 - 07:07:14 EST


ïOn 23-11-15 23:02, Moritz Fischer wrote:
Hi Mike,

thanks for your feedback. I put what I think you suggested inline below.

On Thu, Nov 19, 2015 at 11:25 PM, Mike Looijmans
<mike.looijmans@xxxxxxxx> wrote:
On 19-11-15 23:07, Moritz Fischer wrote:

@@ -457,19 +457,26 @@ static int zynq_fpga_probe(struct platform_device
*pdev)
return err;
}

+ pm_runtime_get_noresume(&pdev->dev);
+ pm_runtime_set_active(&pdev->dev);
+ pm_runtime_enable(&pdev->dev);
+
/* unlock the device */
zynq_fpga_write(priv, UNLOCK_OFFSET, UNLOCK_MASK);

- clk_disable(priv->clk);

err = fpga_mgr_register(dev, "Xilinx Zynq FPGA Manager",
&zynq_fpga_ops, priv);
if (err) {
dev_err(dev, "unable to register FPGA manager");
- clk_unprepare(priv->clk);
+ clk_disable_unprepare(priv->clk);
- clk_disable_unprepare(priv->clk);
+ pm_runtime_put_noidle(&pdev->dev);
+ pm_runtime_disable(&pdev->dev);
return err;
}

+ pm_runtime_put(&pdev->dev);
+
return 0;
}

@@ -483,11 +490,45 @@ static int zynq_fpga_remove(struct platform_device
*pdev)

fpga_mgr_unregister(&pdev->dev);

- clk_unprepare(priv->clk);
+ pm_runtime_get_sync(&pdev->dev);
+ clk_disable_unprepare(priv->clk);
- clk_disable_unprepare(priv->clk);

+ pm_runtime_put_noidle(&pdev->dev);
+ pm_runtime_disable(&pdev->dev);

return 0;
}

+static int __maybe_unused zynq_fpga_runtime_suspend(struct device *dev)
+{
+ struct zynq_fpga_priv *priv;
+ struct fpga_manager *mgr;
+
+ mgr = dev_get_drvdata(dev);
+ priv = mgr->priv;
+
+ clk_disable(priv->clk);

- clk_disable(priv->clk)
+ clk_disable_unprepare(priv->clk)


From what I understand, this call is done in a sleepable context, so you can
use clk_disable_unprepare here (and its counterpart in resume). And remove
the prepare at probe time and unprepare at removal.

Not all clocks can implement atomic enable/disable, for example I2C and SPI
controlled clocks only implement the prepare/unprepare routines.

I guess the "clk" here will always be a SOC provided one, so it won't make
any difference for the Zynq, but someone is likely to some day copy/paste
this driver and use it for some externally connected FPGA instead.

To clarify. Is the above / below what you suggested?

Indeed, that's exactly what I meant.

+static int __maybe_unused zynq_fpga_runtime_resume(struct device *dev)
+{
+ struct zynq_fpga_priv *priv;
+ struct fpga_manager *mgr;
+
+ mgr = dev_get_drvdata(dev);
+ priv = mgr->priv;
+
+ clk_enable(priv->clk);

- clk_enable(priv->clk)
+ clk_prepare_enable(priv->clk)
+
+ return 0;
+}
+

Cheers,

Moritz




Kind regards,

Mike Looijmans
System Expert

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