Re: [PATCH v2] usb: dwc2: add bus suspend/resume for dwc2

From: Julius Werner
Date: Thu Nov 06 2014 - 17:11:38 EST

On Wed, Nov 5, 2014 at 5:30 PM, Kever Yang <kever.yang@xxxxxxxxxxxxxx> wrote:
> Hcd controller needs bus_suspend/resume, dwc2 controller make
> root hub generate suspend/resume signal with hprt0 register
> when work in host mode.
> After the root hub enter suspend, we can make controller enter
> low power state with PCGCTL register.

You say you do this, but I don't actually see you doing it (for the
not-connected case)?

>
> We also update the lx_state for hsotg state.
>
> This patch has tested on rk3288 with suspend/resume.
>
> Signed-off-by: Kever Yang <kever.yang@xxxxxxxxxxxxxx>
> ---
>
> Changes in v2:
> - update commit message
> - make dwc2 suspend/resume sourcecode work
>
> drivers/usb/dwc2/hcd.c | 78 +++++++++++++++++++++++++++++++++++++++++++-------
> 1 file changed, 67 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
> index 0a0e6f0..01a415b 100644
> --- a/drivers/usb/dwc2/hcd.c
> +++ b/drivers/usb/dwc2/hcd.c
> @@ -1471,6 +1471,30 @@ static void dwc2_port_suspend(struct dwc2_hsotg *hsotg, u16 windex)
> }
> }
>
> +static void dwc2_port_resume(struct dwc2_hsotg *hsotg)
> +{
> + u32 hprt0;
> +
> + /* After clear the Stop PHY clock bit, we should wait for a moment
> + * for PLL work stable with clock output.
> + */
> + writel(0, hsotg->regs + PCGCTL);
> + usleep_range(2000, 4000);
> +
> + hprt0 = dwc2_read_hprt0(hsotg);
> + hprt0 |= HPRT0_RES;
> + writel(hprt0, hsotg->regs + HPRT0);
> + hprt0 &= ~HPRT0_SUSP;
> + /* according to USB2.0 Spec 7.1.7.7, the host must send the resume
> + * signal for at least 20ms
> + */
> + usleep_range(20000, 25000);
> +
> + hprt0 &= ~HPRT0_RES;
> + writel(hprt0, hsotg->regs + HPRT0);
> + hsotg->lx_state = DWC2_L0;
> +}
> +
> /* Handles hub class-specific requests */
> static int dwc2_hcd_hub_control(struct dwc2_hsotg *hsotg, u16 typereq,
> u16 wvalue, u16 windex, char *buf, u16 wlength)
> @@ -1516,17 +1540,7 @@ static int dwc2_hcd_hub_control(struct dwc2_hsotg *hsotg, u16 typereq,
> case USB_PORT_FEAT_SUSPEND:
> dev_dbg(hsotg->dev,
> "ClearPortFeature USB_PORT_FEAT_SUSPEND\n");
> - writel(0, hsotg->regs + PCGCTL);
> - usleep_range(20000, 40000);
> -
> - hprt0 = dwc2_read_hprt0(hsotg);
> - hprt0 |= HPRT0_RES;
> - writel(hprt0, hsotg->regs + HPRT0);
> - hprt0 &= ~HPRT0_SUSP;
> - usleep_range(100000, 150000);
> -
> - hprt0 &= ~HPRT0_RES;
> - writel(hprt0, hsotg->regs + HPRT0);

I'm curious why this didn't change lx_state back to DWC2_L0 before...
Paul, do you know?

> + dwc2_port_resume(hsotg);
> break;
>
> case USB_PORT_FEAT_POWER:
> @@ -2299,6 +2313,44 @@ static void _dwc2_hcd_stop(struct usb_hcd *hcd)
> usleep_range(1000, 3000);
> }
>
> +static int _dwc2_hcd_suspend(struct usb_hcd *hcd)
> +{
> + struct dwc2_hsotg *hsotg = dwc2_hcd_to_hsotg(hcd);
> + u32 hprt0;
> +
> + if (!((hsotg->op_state == OTG_STATE_B_HOST) ||
> + (hsotg->op_state == OTG_STATE_A_HOST)))
> + return 0;
> +
> + if (hsotg->lx_state != DWC2_L0)

What if the port is in L1 state? I don't think the driver supports LPM
right now, but the DWC2_L1 enum is defined so it may one day in the
future. Let's maybe at least add a TODO.

> + return 0;

In your original ChromiumOS version of this patch, you also set
PCGCTL_STOPPCLK here if the port was not connected. Is there a reason
that changed (does it not actually save power or something)?

> +
> + hprt0 = dwc2_read_hprt0(hsotg);
> + if (hprt0 & HPRT0_CONNSTS)
> + dwc2_port_suspend(hsotg, 1);

The contract for bus_suspend() is that it will suspend all ports not
yet suspended, keep track of those ports and then only resume those in
bus_resume() (compare, for example, how XHCI keeps track of that with
xhci_bus_state.bus_suspended in xhci_bus_suspend/resume()). So you
need something here to remember whether this function suspended the
port or whether it had already been suspended, and then only resume
the port in bus_resume() in the former case. Note that
dwc2_port_suspend() changes lx_state to DWC_L2 (at least in the
version I'm looking at right now), so you can't just rely on that
unless you explicitly set it back to something else here.

> +
> + return 0;
> +}
> +
> +static int _dwc2_hcd_resume(struct usb_hcd *hcd)
> +{
> + struct dwc2_hsotg *hsotg = dwc2_hcd_to_hsotg(hcd);
> + u32 hprt0;
> +
> + if (!((hsotg->op_state == OTG_STATE_B_HOST) ||
> + (hsotg->op_state == OTG_STATE_A_HOST)))
> + return 0;
> +
> + if (hsotg->lx_state != DWC2_L2)
> + return 0;
> +
> + hprt0 = dwc2_read_hprt0(hsotg);
> + if ((hprt0 & HPRT0_CONNSTS) && (hprt0 & HPRT0_SUSP))
> + dwc2_port_resume(hsotg);
> +
> + return 0;
> +}
> +
> /* Returns the current frame number */
> static int _dwc2_hcd_get_frame_number(struct usb_hcd *hcd)
> {
> @@ -2669,6 +2721,10 @@ static struct hc_driver dwc2_hc_driver = {
> .hub_status_data = _dwc2_hcd_hub_status_data,
> .hub_control = _dwc2_hcd_hub_control,
> .clear_tt_buffer_complete = _dwc2_hcd_clear_tt_buffer_complete,
> +#ifdef CONFIG_PM
> + .bus_suspend = _dwc2_hcd_suspend,
> + .bus_resume = _dwc2_hcd_resume,
> +#endif
> };
>
> /*
> --
> 1.9.1
>
> --
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