Re: [v2,3/3] can: m_can: Add PM Runtime

[Yang, Wenyou]

Hi Franklin,


On 2017/9/21 8:36, Franklin S Cooper Jr wrote:
> On 08/24/2017 03:30 AM, Sekhar Nori wrote:
> > + OMAP mailing list
> >
> > On Tuesday 25 July 2017 04:21 AM, Franklin Cooper wrote:
> > > 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.

> > > 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 <fcooper@xxxxxx>
> > Thanks,
> > Sekhar
> >
> > > ---
> > >   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