On Tuesday 28 March 2017 06:09 AM, Kevin Hilman wrote:
> Alexandre Bailon <abailon@xxxxxxxxxxxx> writes:
>
>> Currently, MUSB DA8xx glue driver doesn't have PM runtime support.
>> Because the CPPI 4.1 is using the same clock as MUSB DA8xx and
>> CPPI 4.1 is a child of MUSB DA8xx glue, add support of PM runtime
>> to the DA8xx glue driver in order to let the CPPI 4.1 driver manage
>> the clock by using PM runtime.
>>
>> Signed-off-by: Alexandre Bailon <abailon@xxxxxxxxxxxx>
>
> Dumb question: even if the clock is shared with cppi4, doesn't the
> use-couting in the clock API handle it so that things should function
> fine even without this patch?
>
> Some other comments/questions below...
>
>> ---
>> drivers/usb/musb/da8xx.c | 27 ++++++++-------------------
>> 1 file changed, 8 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/usb/musb/da8xx.c b/drivers/usb/musb/da8xx.c
>> index ed28afd..89e12f6 100644
>> --- a/drivers/usb/musb/da8xx.c
>> +++ b/drivers/usb/musb/da8xx.c
>> @@ -30,7 +30,6 @@
>> */
>>
>> #include <linux/module.h>
>> -#include <linux/clk.h>
>> #include <linux/err.h>
>> #include <linux/io.h>
>> #include <linux/of_platform.h>
>> @@ -86,7 +85,6 @@ struct da8xx_glue {
>> struct device *dev;
>> struct platform_device *musb;
>> struct platform_device *usb_phy;
>> - struct clk *clk;
>> struct phy *phy;
>> };
>>
>> @@ -376,11 +374,7 @@ static int da8xx_musb_init(struct musb *musb)
>>
>> musb->mregs += DA8XX_MENTOR_CORE_OFFSET;
>>
>> - ret = clk_prepare_enable(glue->clk);
>> - if (ret) {
>> - dev_err(glue->dev, "failed to enable clock\n");
>> - return ret;
>> - }
>> + pm_runtime_get_sync(musb->controller->parent);
>>
>> /* Returns zero if e.g. not clocked */
>> rev = musb_readl(reg_base, DA8XX_USB_REVISION_REG);
>> @@ -423,7 +417,7 @@ static int da8xx_musb_init(struct musb *musb)
>> err_phy_power_on:
>> phy_exit(glue->phy);
>> fail:
>> - clk_disable_unprepare(glue->clk);
>> + pm_runtime_put(musb->controller->parent);
>> return ret;
>> }
>>
>> @@ -435,7 +429,7 @@ static int da8xx_musb_exit(struct musb *musb)
>>
>> phy_power_off(glue->phy);
>> phy_exit(glue->phy);
>> - clk_disable_unprepare(glue->clk);
>> + pm_runtime_put(musb->controller->parent);
>>
>> usb_put_phy(musb->xceiv);
>>
>> @@ -519,7 +513,6 @@ static int da8xx_probe(struct platform_device *pdev)
>> struct musb_hdrc_platform_data *pdata = dev_get_platdata(&pdev->dev);
>> struct da8xx_glue *glue;
>> struct platform_device_info pinfo;
>> - struct clk *clk;
>> struct device_node *np = pdev->dev.of_node;
>> int ret;
>>
>> @@ -527,12 +520,6 @@ static int da8xx_probe(struct platform_device *pdev)
>> if (!glue)
>> return -ENOMEM;
>>
>> - clk = devm_clk_get(&pdev->dev, "usb20");
>> - if (IS_ERR(clk)) {
>> - dev_err(&pdev->dev, "failed to get clock\n");
>> - return PTR_ERR(clk);
>> - }
>
> Something isn't quite right here.
>
> This clk_get uses a con_id "usb20", but when converting to runtime PM,
> we rely on the pm_clk layer (used on davinci for runtime PM) to do clock
> lookups by the default con_ids. I guess this still probably works
> because we fallback to the NULL con_id.
Right, since DaVinci uses pm_clk layer for runtime PM, we support
runtime PM on only two types of clocks. Those with con_id in the list of
con_ids recognized by pm_clk layer or those with NULL con_id. For
devices which use a single clock, NULL con_id is preferred.
Thanks,
Sekhar
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