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SubjectRe: [v2,3/3] can: m_can: Add PM Runtime
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+ 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).

>
> 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@ti.com>

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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