Hi Franklin,


On 2017/9/21 8:36, Franklin S Cooper Jr wrote:

On 08/24/2017 03:30 AM, Sekhar Nori wrote:

quoted

+ OMAP mailing list

On Tuesday 25 July 2017 04:21 AM, Franklin Cooper wrote:

quoted

Add support for PM Runtime which is the new way to handle managing clocks.
However, to avoid breaking SoCs not using PM_RUNTIME leave the old clk
management approach in place.

Since hclk is the interface clock, I think at a minimum there needs to
be an assumption that pm_runtime_get_sync() will enable that clock and
make the module ready for access.

The only in-kernel user of this driver seems to be an atmel SoC. I am
ccing folks who added support for M_CAN on that SoC to see if hclk
management can be left to pm_runtime*() on their SoC.

If they are okay, I think its a good to atleast drop explicit hclk
enable disable in the driver. That way, we avoid double enable/disable
of interface clock (hclk).

Wenyou,

Do you foresee this being a problem on your board? If not I can send a
v3 removing these clk_enable and clk_disable calls and it would be great
if you can test it out and provide your tested by.

Please send a v3 patch.  I would like test it on my side.

quoted

quoted

PM_RUNTIME is required by OMAP based devices to handle clock management.
Therefore, this allows future Texas Instruments SoCs that have the MCAN IP
to work with this driver.

Signed-off-by: Franklin S Cooper Jr <redacted>

Thanks,
Sekhar

quoted

---
  drivers/net/can/m_can/m_can.c | 13 +++++++++++++
  1 file changed, 13 insertions(+)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index ea48e59..93e23f5 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c

@@ -23,6 +23,7 @@
  #include <linux/of.h>
  #include <linux/of_device.h>
  #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
  #include <linux/iopoll.h>
  #include <linux/can/dev.h>
  

@@ -633,11 +634,15 @@ static int m_can_clk_start(struct m_can_priv *priv)
  	if (err)
  		clk_disable_unprepare(priv->hclk);
  
+	pm_runtime_get_sync(priv->device);
+
  	return err;
  }
  
  static void m_can_clk_stop(struct m_can_priv *priv)
  {
+	pm_runtime_put_sync(priv->device);
+
  	clk_disable_unprepare(priv->cclk);
  	clk_disable_unprepare(priv->hclk);
  }

@@ -1582,6 +1587,8 @@ static int m_can_plat_probe(struct platform_device *pdev)
  	/* Enable clocks. Necessary to read Core Release in order to determine
  	 * M_CAN version
  	 */
+	pm_runtime_enable(&pdev->dev);
+
  	ret = clk_prepare_enable(hclk);
  	if (ret)
  		goto disable_hclk_ret;

@@ -1626,6 +1633,8 @@ static int m_can_plat_probe(struct platform_device *pdev)
  	 */
  	tx_fifo_size = mram_config_vals[7];
  
+	pm_runtime_get_sync(&pdev->dev);
+
  	/* allocate the m_can device */
  	dev = alloc_m_can_dev(pdev, addr, tx_fifo_size);
  	if (!dev) {

@@ -1670,6 +1679,7 @@ static int m_can_plat_probe(struct platform_device *pdev)
  disable_hclk_ret:
  	clk_disable_unprepare(hclk);
  failed_ret:
+	pm_runtime_put_sync(&pdev->dev);
  	return ret;
  }
  

@@ -1726,6 +1736,9 @@ static int m_can_plat_remove(struct platform_device *pdev)
  	struct net_device *dev = platform_get_drvdata(pdev);
  
  	unregister_m_can_dev(dev);
+
+	pm_runtime_disable(&pdev->dev);
+
  	platform_set_drvdata(pdev, NULL);
  
  	free_m_can_dev(dev);

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Best Regards,
Wenyou Yang