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

[Mathias Nyman <mathias.nyman@linux.intel.com>]

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@apm.com> wrote:
>> From: Tung Nguyen <tunguyen@apm.com>
>>
>> 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@apm.com>
>> Signed-off-by: Thang Q. Nguyen <tqnguyen@apm.com>
>> ---
>>   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