linux-kernel - Re: [PATCH 2/3] usb: xhci: tegra: Add runtime PM support

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Message-ID: <54bd00b7-2835-a253-0399-370e8c8203b8@linux.intel.com>
Date:   Thu, 1 Mar 2018 16:18:09 +0200
From:   Mathias Nyman <mathias.nyman@...ux.intel.com>
To:     Jon Hunter <jonathanh@...dia.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thierry Reding <thierry.reding@...il.com>
Cc:     linux-usb@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] usb: xhci: tegra: Add runtime PM support

On 14.02.2018 18:34, Jon Hunter wrote:
> Add runtime PM support to the Tegra XHCI driver and move the function
> calls to enable/disable the clocks, regulators and PHY into the runtime
> PM callbacks.
> 
> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
> ---
>   drivers/usb/host/xhci-tegra.c | 80 ++++++++++++++++++++++++++++++-------------
>   1 file changed, 56 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
> index 02b0b24faa58..42aa67858b53 100644
> --- a/drivers/usb/host/xhci-tegra.c
> +++ b/drivers/usb/host/xhci-tegra.c
> @@ -18,6 +18,7 @@
>   #include <linux/phy/tegra/xusb.h>
>   #include <linux/platform_device.h>
>   #include <linux/pm.h>
> +#include <linux/pm_runtime.h>
>   #include <linux/regulator/consumer.h>
>   #include <linux/reset.h>
>   #include <linux/slab.h>
> @@ -1067,22 +1068,12 @@ static int tegra_xusb_probe(struct platform_device *pdev)
>   	 */
>   	platform_set_drvdata(pdev, tegra);
>   
> -	err = tegra_xusb_clk_enable(tegra);
> -	if (err) {
> -		dev_err(&pdev->dev, "failed to enable clocks: %d\n", err);
> -		goto put_usb2;
> -	}
> -
> -	err = regulator_bulk_enable(tegra->soc->num_supplies, tegra->supplies);
> -	if (err) {
> -		dev_err(&pdev->dev, "failed to enable regulators: %d\n", err);
> -		goto disable_clk;
> -	}
> +	pm_runtime_enable(&pdev->dev);
>   
> -	err = tegra_xusb_phy_enable(tegra);
> +	err = pm_runtime_get_sync(&pdev->dev);
>   	if (err < 0) {

Does this mean that if runtime PM is disabled then clocks and regulator will never be enabled
for Tegra xhci?

How about keeping the clock and regualtor enabling in probe, and instead add something like:

pm_runtime_set_active(&pdev->dev);
pm_runtime_enable(&pdev->dev);
pm_runtime_get_noresume(&pdev->dev);

-Mathias