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

>
>>
>> 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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