[0/3] Fix cold plugged USB device on certain PCIe USB cards

Cold plugged USB device was not detected on certain PCIe USB cards
(like Inateck card connected to AM64 EVM or connected to J7200 EVM).

Re-plugging the USB device always gets it enumerated.

This issue was discussed in
https://lore.kernel.org/r/772e4001-178e-4918-032c-6e625bdded24@ti.com
and
https://bugzilla.kernel.org/show_bug.cgi?id=214021

So the suggested solution is to register both root hubs along with the
second hcd for xhci.

RFC Patch series can be found at [1]

Changes from RFC:
1) Mathias identified potential issues with the RFC patch [2] and suggested
   the solution to use HCD flags. This series implements it.

[1] -> https://lore.kernel.org/linux-usb/20210824105302.25382-1-kishon@ti.com/ 
[2] -> https://lore.kernel.org/linux-usb/06693934-28f2-d59e-b004-62cabd3f9e8e@linux.intel.com

Kishon Vijay Abraham I (3):
  usb: core: hcd: Modularize HCD stop configuration in usb_stop_hcd()
  usb: core: hcd: Add support for deferring roothub registration
  xhci: Set HCD flag to defer primary roothub registration

 drivers/usb/core/hcd.c  | 67 +++++++++++++++++++++++++++--------------
 drivers/usb/host/xhci.c |  2 +-
 include/linux/usb/hcd.h |  2 ++
 3 files changed, 48 insertions(+), 23 deletions(-)

On Wed, Aug 25, 2021 at 04:21:30PM +0530, Kishon Vijay Abraham I wrote:
> No functional change. Since configuration to stop HCD is invoked from
> multiple places, group all of them in usb_stop_hcd().
> 
> Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
> ---
>  drivers/usb/core/hcd.c | 39 ++++++++++++++++++++++-----------------
>  1 file changed, 22 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
> index 0f8b7c93310e..775f0456f0ad 100644
> --- a/drivers/usb/core/hcd.c
> +++ b/drivers/usb/core/hcd.c
> @@ -2760,6 +2760,26 @@ static void usb_put_invalidate_rhdev(struct usb_hcd *hcd)
>  	usb_put_dev(rhdev);
>  }
>  
> +/**
> + * usb_stop_hcd - Halt the HCD
> + * @hcd: the usb_hcd that has to be halted
> + *
> + * Stop the timer and invoke ->stop() callback on the HCD

This comment is now somewhat out of context.  It should be rephrased 
to say "Stop the root-hub polling timer and invoke the HCD's ->stop 
callback."

Apart from that,

Acked-by: Alan Stern <stern@rowland.harvard.edu>

Alan Stern

> + */
> +static void usb_stop_hcd(struct usb_hcd *hcd)
> +{
> +	hcd->rh_pollable = 0;
> +	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
> +	del_timer_sync(&hcd->rh_timer);
> +
> +	hcd->driver->stop(hcd);
> +	hcd->state = HC_STATE_HALT;
> +
> +	/* In case the HCD restarted the timer, stop it again. */
> +	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
> +	del_timer_sync(&hcd->rh_timer);
> +}
> +
>  /**
>   * usb_add_hcd - finish generic HCD structure initialization and register
>   * @hcd: the usb_hcd structure to initialize
> @@ -2946,13 +2966,7 @@ int usb_add_hcd(struct usb_hcd *hcd,
>  	return retval;
>  
>  err_register_root_hub:
> -	hcd->rh_pollable = 0;
> -	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
> -	del_timer_sync(&hcd->rh_timer);
> -	hcd->driver->stop(hcd);
> -	hcd->state = HC_STATE_HALT;
> -	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
> -	del_timer_sync(&hcd->rh_timer);
> +	usb_stop_hcd(hcd);
>  err_hcd_driver_start:
>  	if (usb_hcd_is_primary_hcd(hcd) && hcd->irq > 0)
>  		free_irq(irqnum, hcd);
> @@ -3022,16 +3036,7 @@ void usb_remove_hcd(struct usb_hcd *hcd)
>  	 * interrupt occurs), but usb_hcd_poll_rh_status() won't invoke
>  	 * the hub_status_data() callback.
>  	 */
> -	hcd->rh_pollable = 0;
> -	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
> -	del_timer_sync(&hcd->rh_timer);
> -
> -	hcd->driver->stop(hcd);
> -	hcd->state = HC_STATE_HALT;
> -
> -	/* In case the HCD restarted the timer, stop it again. */
> -	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
> -	del_timer_sync(&hcd->rh_timer);
> +	usb_stop_hcd(hcd);
>  
>  	if (usb_hcd_is_primary_hcd(hcd)) {
>  		if (hcd->irq > 0)
> -- 
> 2.17.1
>