On Wed, Sep 08, 2021 at 03:23:10PM +0530, Kishon Vijay Abraham I wrote:
> It has been observed with certain PCIe USB cards (like Inateck connected
> to AM64 EVM or J7200 EVM) that as soon as the primary roothub is
> registered, port status change is handled even before xHC is running
> leading to cold plug USB devices not detected. For such cases, registering
> both the root hubs along with the second HCD is required. Add support for
> deferring roothub registration in usb_add_hcd(), so that both primary and
> secondary roothubs are registered along with the second HCD.
>
> CC: stable@xxxxxxxxxxxxxxx # 5.4+
> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
> Suggested-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
> Tested-by: Chris Chiu <chris.chiu@xxxxxxxxxxxxx>
> ---
> drivers/usb/core/hcd.c | 30 ++++++++++++++++++++++++------
> include/linux/usb/hcd.h | 2 ++
> 2 files changed, 26 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
> index 0f8b7c93310e..30bbf4ac4284 100644
> --- a/drivers/usb/core/hcd.c
> +++ b/drivers/usb/core/hcd.c
> @@ -2775,6 +2775,7 @@ int usb_add_hcd(struct usb_hcd *hcd,
> {
> int retval;
> struct usb_device *rhdev;
> + struct usb_hcd *shared_hcd;
>
> if (!hcd->skip_phy_initialization && usb_hcd_is_primary_hcd(hcd)) {
> hcd->phy_roothub = usb_phy_roothub_alloc(hcd->self.sysdev);
> @@ -2935,13 +2936,26 @@ int usb_add_hcd(struct usb_hcd *hcd,
> goto err_hcd_driver_start;
> }
>
> + /* starting here, usbcore will pay attention to the shared HCD roothub */
> + shared_hcd = hcd->shared_hcd;
> + if (!usb_hcd_is_primary_hcd(hcd) && shared_hcd && HCD_DEFER_RH_REGISTER(shared_hcd)) {
> + retval = register_root_hub(shared_hcd);
> + if (retval != 0)
> + goto err_register_root_hub;
> +
> + if (shared_hcd->uses_new_polling && HCD_POLL_RH(shared_hcd))
> + usb_hcd_poll_rh_status(shared_hcd);
> + }
> +
> /* starting here, usbcore will pay attention to this root hub */
> - retval = register_root_hub(hcd);
> - if (retval != 0)
> - goto err_register_root_hub;
> + if (!HCD_DEFER_RH_REGISTER(hcd)) {
> + retval = register_root_hub(hcd);
> + if (retval != 0)
> + goto err_register_root_hub;
>
> - if (hcd->uses_new_polling && HCD_POLL_RH(hcd))
> - usb_hcd_poll_rh_status(hcd);
> + if (hcd->uses_new_polling && HCD_POLL_RH(hcd))
> + usb_hcd_poll_rh_status(hcd);
> + }
>
> return retval;
>
> @@ -2985,6 +2999,7 @@ EXPORT_SYMBOL_GPL(usb_add_hcd);
> void usb_remove_hcd(struct usb_hcd *hcd)
> {
> struct usb_device *rhdev = hcd->self.root_hub;
> + unsigned rh_registered;
This really should be a bool, not an unsigned. (Relatively unimportant.)
> dev_info(hcd->self.controller, "remove, state %x\n", hcd->state);
>
> @@ -2995,6 +3010,8 @@ void usb_remove_hcd(struct usb_hcd *hcd)
>
> dev_dbg(hcd->self.controller, "roothub graceful disconnect\n");
> spin_lock_irq (&hcd_root_hub_lock);
> + if (hcd->rh_registered == 1)
> + rh_registered = 1;
Just say: rh_registered = hcd->rh_registered
> hcd->rh_registered = 0;
> spin_unlock_irq (&hcd_root_hub_lock);
>
> @@ -3004,7 +3021,8 @@ void usb_remove_hcd(struct usb_hcd *hcd)
> cancel_work_sync(&hcd->died_work);
>
> mutex_lock(&usb_bus_idr_lock);
> - usb_disconnect(&rhdev); /* Sets rhdev to NULL */
> + if (rh_registered == 1)
Just say: if (rh_registered)
> + usb_disconnect(&rhdev); /* Sets rhdev to NULL */
Didn't the compiler warn about using a possibly uninitialized variable?
The overall logic looks okay, apart from this one point.
Alan Stern
> mutex_unlock(&usb_bus_idr_lock);
>
> /*
> diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
> index 548a028f2dab..2c1fc9212cf2 100644
> --- a/include/linux/usb/hcd.h
> +++ b/include/linux/usb/hcd.h
> @@ -124,6 +124,7 @@ struct usb_hcd {
> #define HCD_FLAG_RH_RUNNING 5 /* root hub is running? */
> #define HCD_FLAG_DEAD 6 /* controller has died? */
> #define HCD_FLAG_INTF_AUTHORIZED 7 /* authorize interfaces? */
> +#define HCD_FLAG_DEFER_RH_REGISTER 8 /* Defer roothub registration */
>
> /* The flags can be tested using these macros; they are likely to
> * be slightly faster than test_bit().
> @@ -134,6 +135,7 @@ struct usb_hcd {
> #define HCD_WAKEUP_PENDING(hcd) ((hcd)->flags & (1U << HCD_FLAG_WAKEUP_PENDING))
> #define HCD_RH_RUNNING(hcd) ((hcd)->flags & (1U << HCD_FLAG_RH_RUNNING))
> #define HCD_DEAD(hcd) ((hcd)->flags & (1U << HCD_FLAG_DEAD))
> +#define HCD_DEFER_RH_REGISTER(hcd) ((hcd)->flags & (1U << HCD_FLAG_DEFER_RH_REGISTER))
>
> /*
> * Specifies if interfaces are authorized by default
> --
> 2.17.1
>
