[v3] usb: warm-reset ports on hub resume, if requested

[Jan-Marek Glogowski <glogow@fbihome.de>]

Just adding some CC of commit signers from get_maintainer.pl

Am 16.01.19 um 18:07 schrieb Jan-Marek Glogowski:
> On plug-in of my USB-C device, its USB_SS_PORT_LS_SS_INACTIVE
> link state bit is set. Greping all the kernel for this bit shows
> that the port status requests a warm-reset this way.
> 
> This just happens, if its the only device on that hub and the 
> hub resumes, so we don't call port_event, which would otherwise
> warm-reset ports. The device works ok without this patch, if
> there is already any other device connected to the hub.
> 
> Signed-off-by: Jan-Marek Glogowski <glogow@fbihome.de>
> ---
> 
> v1: This always warm-resets the ports in hub_activate, independent of the
> "enum hub_activation_type". Just had a single device to test.
> 
> v2: I had the idea about the working device, if there is already a device
> connected to the hub and that a resume only on "type == HUB_RESUME" should
> be sufficient. This still works for me, but I didn't follow all the
> hub_activate callers everywhere and I'm definitly still missing a lot of
> knowledge about USB stuff. There is also HUB_RESET_RESUME with a slightly
> different code path. I don't know how to trigger this.
> 
> v3: code unchanged to v2, so I could abandon my explanation mail, which I
> was typing when Gregs mail arrived.
> 
> ---
>  drivers/usb/core/hub.c | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 1d1e61e..e0cc740 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -108,6 +108,16 @@ EXPORT_SYMBOL_GPL(ehci_cf_port_reset_rwsem);
>  static void hub_release(struct kref *kref);
>  static int usb_reset_and_verify_device(struct usb_device *udev);
>  static int hub_port_disable(struct usb_hub *hub, int port1, int set_state);
> +static bool hub_port_warm_reset_required(struct usb_hub *hub, int port1,
> +		u16 portstatus);
> +static int hub_port_reset(struct usb_hub *hub, int port1,
> +			struct usb_device *udev, unsigned int delay, bool warm);
> +
> +#define HUB_ROOT_RESET_TIME	60	/* times are in msec */
> +#define HUB_SHORT_RESET_TIME	10
> +#define HUB_BH_RESET_TIME	50
> +#define HUB_LONG_RESET_TIME	200
> +#define HUB_RESET_TIMEOUT	800
>  
>  static inline char *portspeed(struct usb_hub *hub, int portstatus)
>  {
> @@ -1122,6 +1132,11 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
>  						USB_SS_PORT_LS_POLLING))
>  			need_debounce_delay = true;
>  
> +		if (type == HUB_RESUME &&
> +		    hub_port_warm_reset_required(hub, port1, portstatus))
> +			hub_port_reset(hub, port1, udev,
> +					HUB_BH_RESET_TIME, true);
> +
>  		/* Clear status-change flags; we'll debounce later */
>  		if (portchange & USB_PORT_STAT_C_CONNECTION) {
>  			need_debounce_delay = true;
> @@ -2653,12 +2668,6 @@ static unsigned hub_is_wusb(struct usb_hub *hub)
>  #define SET_CONFIG_TRIES	(2 * (use_both_schemes + 1))
>  #define USE_NEW_SCHEME(i, scheme)	((i) / 2 == (int)scheme)
>  
> -#define HUB_ROOT_RESET_TIME	60	/* times are in msec */
> -#define HUB_SHORT_RESET_TIME	10
> -#define HUB_BH_RESET_TIME	50
> -#define HUB_LONG_RESET_TIME	200
> -#define HUB_RESET_TIMEOUT	800
> -
>  /*
>   * "New scheme" enumeration causes an extra state transition to be
>   * exposed to an xhci host and causes USB3 devices to receive control
>