Re: [PATCH v1 1/1] usb: xhci: do not create and register shared_hcd when USB3.0 is disabled

[Mathias Nyman]

Hi, Sorry about the delay

On 04.01.2018 07:17, Thang Q. Nguyen wrote:
> Hi,
>
> On Sat, Dec 16, 2017 at 10:45 AM, Thang Q. Nguyen <tqnguyen@xxxxxxx> wrote:
> > From: Tung Nguyen <tunguyen@xxxxxxx>
> >
> > Currently, hcd->shared_hcd always creates and registers to the usb-core.
> > If, for some reasons, USB3 downstream port is disabled, no roothub port for
> > USB3.0 is found. This causes kernel to display an error:
> > hub 2-0:1.0: config failed, hub doesn't have any ports! (err -19)
> > This patch checks, creates and registers shared_hcd if USB3.0 downstream
> > port is available.
> >
> > Signed-off-by: Tung Nguyen <tunguyen@xxxxxxx>
> > Signed-off-by: Thang Q. Nguyen <tqnguyen@xxxxxxx>
> > ---
> >   drivers/usb/host/xhci-mem.c  |  2 +-
> >   drivers/usb/host/xhci-plat.c | 26 +++++++++++----------
> >   drivers/usb/host/xhci.c      | 54 ++++++++++++++++++++++++++++++++------------
> >   3 files changed, 54 insertions(+), 28 deletions(-)
> >
> > diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
> > index 554a8a5..157d1e7 100644
> > --- a/drivers/usb/host/xhci-mem.c
> > +++ b/drivers/usb/host/xhci-mem.c
> > @@ -1067,7 +1067,7 @@ static u32 xhci_find_real_port_number(struct xhci_hcd *xhci,
> >          struct usb_device *top_dev;
> >          struct usb_hcd *hcd;
> >
> > -       if (udev->speed >= USB_SPEED_SUPER)
> > +       if (udev->speed >= USB_SPEED_SUPER && xhci->shared_hcd)
> >                  hcd = xhci->shared_hcd;
> >          else
> >                  hcd = xhci->main_hcd;
> > diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> > index 6f03830..e812e3d 100644
> > --- a/drivers/usb/host/xhci-plat.c
> > +++ b/drivers/usb/host/xhci-plat.c
> > @@ -253,12 +253,6 @@ static int xhci_plat_probe(struct platform_device *pdev)
> >
> >          xhci->clk = clk;
> >          xhci->main_hcd = hcd;
> > -       xhci->shared_hcd = __usb_create_hcd(driver, sysdev, &pdev->dev,
> > -                       dev_name(&pdev->dev), hcd);
> > -       if (!xhci->shared_hcd) {
> > -               ret = -ENOMEM;
> > -               goto disable_clk;
> > -       }
> >
> >          if (device_property_read_bool(sysdev, "usb2-lpm-disable"))
> >                  xhci->quirks |= XHCI_HW_LPM_DISABLE;
> > @@ -290,12 +284,20 @@ static int xhci_plat_probe(struct platform_device *pdev)
> >          if (ret)
> >                  goto disable_usb_phy;
> >
> > -       if (HCC_MAX_PSA(xhci->hcc_params) >= 4)
> > -               xhci->shared_hcd->can_do_streams = 1;
> > -
> > -       ret = usb_add_hcd(xhci->shared_hcd, irq, IRQF_SHARED);
> > -       if (ret)
> > -               goto dealloc_usb2_hcd;
> > +       if (xhci->num_usb3_ports > 0) {
> > +               xhci->shared_hcd = __usb_create_hcd(driver, sysdev, &pdev->dev,
> > +                               dev_name(&pdev->dev), hcd);
> > +               if (!xhci->shared_hcd) {
> > +                       ret = -ENOMEM;
> > +                       goto disable_clk;
> > +               }
> > +               if (HCC_MAX_PSA(xhci->hcc_params) >= 4)
> > +                       xhci->shared_hcd->can_do_streams = 1;
> > +
> > +               ret = usb_add_hcd(xhci->shared_hcd, irq, IRQF_SHARED);
> > +               if (ret)
> > +                       goto dealloc_usb2_hcd;
> > +       }
> >
> >          device_enable_async_suspend(&pdev->dev);
> >          pm_runtime_put_noidle(&pdev->dev);
> > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> > index 05104bd..4824bf6 100644
> > --- a/drivers/usb/host/xhci.c
> > +++ b/drivers/usb/host/xhci.c
> > @@ -417,12 +417,14 @@ static void compliance_mode_recovery(struct timer_list *t)
> >                                          i + 1);
> >                          xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
> >                                          "Attempting compliance mode recovery");
> > -                       hcd = xhci->shared_hcd;
> > +                       if (xhci->shared_hcd) {
> > +                               hcd = xhci->shared_hcd;
> >
> > -                       if (hcd->state == HC_STATE_SUSPENDED)
> > -                               usb_hcd_resume_root_hub(hcd);
> > +                               if (hcd->state == HC_STATE_SUSPENDED)
> > +                                       usb_hcd_resume_root_hub(hcd);
> >
> > -                       usb_hcd_poll_rh_status(hcd);
> > +                               usb_hcd_poll_rh_status(hcd);
> > +                       }
> >                  }
> >          }
> >
> > @@ -611,6 +613,18 @@ int xhci_run(struct usb_hcd *hcd)
> >                  if (ret)
> >                          xhci_free_command(xhci, command);
> >          }
> > +       /*
> > +        * Execute xhci_start() in case xhci->shared_hcd is not registered.
> > +        * If the xhci->shared_hcd doesn't exist, no one triggers to start
> > +        * the xhci which should be done before exitting run function
> > +        */
> > +       if (!xhci->shared_hcd) {
> > +               if (xhci_start(xhci)) {

This probably won't work as primary hcd was added before shared_hcd was created.
usb_add_hcd(hcd) calls xhci_run() before xhci->shared_hcd exists, so this will
cause the xHC to start before the shared_hcd is created or setup.

-Mathias