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SubjectRe: [v2,3/3] can: m_can: Add PM Runtime
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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@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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Best Regards,
Wenyou Yang

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