[PATCHv2 2/2] USB: host: ohci_at91: Stop/start USB PLL for all sleep modes

[boris.brezillon@free-electrons.com (Boris Brezillon)]

On Sat, 17 Jan 2015 16:36:35 +0100
Sylvain Rochet <sylvain.rochet@finsecur.com> wrote:

> Disable/unprepare clocks without testing the sleep target_state, removed
> the at91_suspend_entering_slow_clock() call (which is only a
> target_state == PM_SUSPEND_MEM).
> 
> Other kind of suspend now benefit from the power save induced by this
> PLL deactivation. The resume penalty is about 500 us, which is not
> negligible but acceptable considering the amount of power we are saving.
> 
> Signed-off-by: Sylvain Rochet <sylvain.rochet@finsecur.com>
> Reported-by: Boris Brezillon <boris.brezillon@free-electrons.com>

Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>

> ---
>  drivers/usb/host/ohci-at91.c | 25 +++++++++++++------------
>  1 file changed, 13 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/usb/host/ohci-at91.c b/drivers/usb/host/ohci-at91.c
> index dc9e4e6..f0da734 100644
> --- a/drivers/usb/host/ohci-at91.c
> +++ b/drivers/usb/host/ohci-at91.c
> @@ -49,6 +49,8 @@ extern int usb_disabled(void);
>  
>  static void at91_start_clock(void)
>  {
> +	if (clocked)
> +		return;
>  	if (IS_ENABLED(CONFIG_COMMON_CLK)) {
>  		clk_set_rate(uclk, 48000000);
>  		clk_prepare_enable(uclk);
> @@ -61,6 +63,8 @@ static void at91_start_clock(void)
>  
>  static void at91_stop_clock(void)
>  {
> +	if (!clocked)
> +		return;
>  	clk_disable_unprepare(fclk);
>  	clk_disable_unprepare(iclk);
>  	clk_disable_unprepare(hclk);
> @@ -615,16 +619,14 @@ ohci_hcd_at91_drv_suspend(struct platform_device *pdev, pm_message_t mesg)
>  	 *
>  	 * REVISIT: some boards will be able to turn VBUS off...
>  	 */
> -	if (at91_suspend_entering_slow_clock()) {
> -		ohci->hc_control = ohci_readl(ohci, &ohci->regs->control);
> -		ohci->hc_control &= OHCI_CTRL_RWC;
> -		ohci_writel(ohci, ohci->hc_control, &ohci->regs->control);
> -		ohci->rh_state = OHCI_RH_HALTED;
> -
> -		/* flush the writes */
> -		(void) ohci_readl (ohci, &ohci->regs->control);
> -		at91_stop_clock();
> -	}
> +	ohci->hc_control = ohci_readl(ohci, &ohci->regs->control);
> +	ohci->hc_control &= OHCI_CTRL_RWC;
> +	ohci_writel(ohci, ohci->hc_control, &ohci->regs->control);
> +	ohci->rh_state = OHCI_RH_HALTED;
> +
> +	/* flush the writes */
> +	(void) ohci_readl (ohci, &ohci->regs->control);
> +	at91_stop_clock();
>  
>  	return ret;
>  }
> @@ -636,8 +638,7 @@ static int ohci_hcd_at91_drv_resume(struct platform_device *pdev)
>  	if (device_may_wakeup(&pdev->dev))
>  		disable_irq_wake(hcd->irq);
>  
> -	if (!clocked)
> -		at91_start_clock();
> +	at91_start_clock();
>  
>  	ohci_resume(hcd, false);
>  	return 0;



-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com