Subject: [PATCH v2] usb: gadget: at91_udc: move prepare clk into process context

From: [email-masked] (Mike Turquette)
Date: Mon, 11 Aug 2014 20:34:56 -0700

Quoting Ronald Wahl (2014-08-06 06:11:42)
> Commit 7628083227b6bc4a7e33d7c381d7a4e558424b6b added clock preparation in
> interrupt context. This is not allowed as it might sleep. Move clock
> preparation into process context (at91udc_probe).
> ---
>  drivers/usb/gadget/udc/at91_udc.c | 39 ++++++++++++++++++++++++++++++---------
>  1 file changed, 30 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/at91_udc.c b/drivers/usb/gadget/udc/at91_udc.c
> index cfd18bc..0b347a0 100644
> --- a/drivers/usb/gadget/udc/at91_udc.c
> +++ b/drivers/usb/gadget/udc/at91_udc.c
> @@ -872,10 +872,10 @@ static void clk_on(struct at91_udc *udc)
>  
>         if (IS_ENABLED(CONFIG_COMMON_CLK)) {

Why is this check necessary at all? Drivers shouldn't have to care at
all about the underlying clock framework implementation.

>                 clk_set_rate(udc->uclk, 48000000);
> -               clk_prepare_enable(udc->uclk);
> +               clk_enable(udc->uclk);
>         }
> -       clk_prepare_enable(udc->iclk);
> -       clk_prepare_enable(udc->fclk);
> +       clk_enable(udc->iclk);
> +       clk_enable(udc->fclk);
>  }
>  
>  static void clk_off(struct at91_udc *udc)
> @@ -884,10 +884,10 @@ static void clk_off(struct at91_udc *udc)
>                 return;
>         udc->clocked = 0;
>         udc->gadget.speed = USB_SPEED_UNKNOWN;
> -       clk_disable_unprepare(udc->fclk);
> -       clk_disable_unprepare(udc->iclk);
> +       clk_disable(udc->fclk);
> +       clk_disable(udc->iclk);
>         if (IS_ENABLED(CONFIG_COMMON_CLK))
> -               clk_disable_unprepare(udc->uclk);
> +               clk_disable(udc->uclk);
>  }
>  
>  /*
> @@ -1780,14 +1780,23 @@ static int at91udc_probe(struct platform_device *pdev)
>         }
>  
>         /* don't do anything until we have both gadget driver and VBUS */
> +       if (IS_ENABLED(CONFIG_COMMON_CLK)) {

Same question here. What does the clock framework implementation have to
do with uclk?

Regards,
Mike