On 10/16/2015 3:10 PM, Douglas Anderson wrote:
> If you've got your interrupt signals bouncing a bit as you insert your
> USB device, you might end up in a state when the device is connected but
> the driver doesn't know it.
>
> Specifically, the observed order is:
> 1. hardware sees connect
> 2. hardware sees disconnect
> 3. hardware sees connect
> 4. dwc2_port_intr() - clears connect interrupt
> 5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect()
>
> Now you'll be stuck with the cable plugged in and no further interrupts
> coming in but the driver will think we're disconnected.
>
> We'll fix this by checking for the missing connect interrupt and
> re-connecting after the disconnect is posted. We don't skip the
> disconnect because if there is a transitory disconnect we really want to
> de-enumerate and re-enumerate.
>
> Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> ---
> drivers/usb/dwc2/core.h | 2 ++
> drivers/usb/dwc2/hcd.c | 33 +++++++++++++++++++++++++++++++++
> drivers/usb/dwc2/hcd_intr.c | 6 +-----
> 3 files changed, 36 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
> index ebf2504..30748be 100644
> --- a/drivers/usb/dwc2/core.h
> +++ b/drivers/usb/dwc2/core.h
> @@ -1151,11 +1151,13 @@ static inline int dwc2_hsotg_set_test_mode(struct dwc2_hsotg *hsotg,
>
> #if IS_ENABLED(CONFIG_USB_DWC2_HOST) || IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE)
> extern int dwc2_hcd_get_frame_number(struct dwc2_hsotg *hsotg);
> +extern void dwc2_hcd_connect(struct dwc2_hsotg *hsotg);
> extern void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg);
> extern void dwc2_hcd_start(struct dwc2_hsotg *hsotg);
> #else
> static inline int dwc2_hcd_get_frame_number(struct dwc2_hsotg *hsotg)
> { return 0; }
> +static inline void dwc2_hcd_connect(struct dwc2_hsotg *hsotg) {}
> static inline void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg) {}
> static inline void dwc2_hcd_start(struct dwc2_hsotg *hsotg) {}
> static inline void dwc2_hcd_remove(struct dwc2_hsotg *hsotg) {}
> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
> index af4e4a2..4d2bc50 100644
> --- a/drivers/usb/dwc2/hcd.c
> +++ b/drivers/usb/dwc2/hcd.c
> @@ -268,6 +268,22 @@ static void dwc2_hcd_cleanup_channels(struct dwc2_hsotg *hsotg)
> }
>
> /**
> + * dwc2_hcd_connect() - Handles connect of the HCD
> + *
> + * @hsotg: Pointer to struct dwc2_hsotg
> + *
> + * Must be called with interrupt disabled and spinlock held
> + */
> +void dwc2_hcd_connect(struct dwc2_hsotg *hsotg)
> +{
> + if (hsotg->lx_state != DWC2_L0)
> + usb_hcd_resume_root_hub(hsotg->priv);
> +
> + hsotg->flags.b.port_connect_status_change = 1;
> + hsotg->flags.b.port_connect_status = 1;
> +}
> +
> +/**
> * dwc2_hcd_disconnect() - Handles disconnect of the HCD
> *
> * @hsotg: Pointer to struct dwc2_hsotg
> @@ -277,6 +293,7 @@ static void dwc2_hcd_cleanup_channels(struct dwc2_hsotg *hsotg)
> void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg)
> {
> u32 intr;
> + u32 hprt0;
>
> /* Set status flags for the hub driver */
> hsotg->flags.b.port_connect_status_change = 1;
> @@ -315,6 +332,22 @@ void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg)
> dwc2_hcd_cleanup_channels(hsotg);
>
> dwc2_host_disconnect(hsotg);
> +
> + /*
> + * Add an extra check here to see if we're actually connected but
> + * we don't have a detection interrupt pending. This can happen if:
> + * 1. hardware sees connect
> + * 2. hardware sees disconnect
> + * 3. hardware sees connect
> + * 4. dwc2_port_intr() - clears connect interrupt
> + * 5. dwc2_handle_common_intr() - calls here
> + *
> + * Without the extra check here we will end calling disconnect
> + * and won't get any future interrupts to handle the connect.
> + */
> + hprt0 = dwc2_readl(hsotg->regs + HPRT0);
> + if (!(hprt0 & HPRT0_CONNDET) && (hprt0 & HPRT0_CONNSTS))
> + dwc2_hcd_connect(hsotg);
I'm a little bit wary of this as it will also run when you unload
the module with a device connected. However I can't produce any
negative results from that. Will it work if you handle it just
for the disconnect interrupt?
John
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