Re: [PATCH] usb: musb: fix idling for suspend after disconnect interrupt

[Bin Liu <b-liu@ti.com>]

Hi Tony,

Sorry for my late response.

On Mon, Nov 25, 2019 at 07:41:51PM -0800, Tony Lindgren wrote:
> When disconnected as USB B-device, we sometimes get a suspend interrupt
> after disconnect interrupt. In that case we have devctl set to 99 with
> VBUS still valid and musb_pm_runtime_check_session() wrongly things we
> have an active session. We have no other interrupts after disconnect
> coming in this case at least with the omap2430 glue.

I don't have an omap2430 platform to test, but its musb doesn't generate
DISCONNECT interrupt at all when disconnected from USB host in any case?
It is a surprise, the musb core driver expects the DISCONNECT interrupt
after VBUS is lost and relies on it to tear down the gadget driver and
the state machine. I am wondering how its USB is functional without the
DISCONNECT event...

-Bin.

> 
> Let's fix the issue by checking the interrupt status again with
> delayed work for the devctl 99 case. In the suspend after disconnect
> case the devctl session bit has cleared by then and musb can idle.
> For a typical USB B-device connect case we just continue with normal
> interrupts.
> 
> Cc: Merlijn Wajer <merlijn@wizzup.org>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Sebastian Reichel <sre@kernel.org>
> Signed-off-by: Tony Lindgren <tony@atomide.com>
> ---
>  drivers/usb/musb/musb_core.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
> --- a/drivers/usb/musb/musb_core.c
> +++ b/drivers/usb/musb/musb_core.c
> @@ -1943,6 +1943,9 @@ ATTRIBUTE_GROUPS(musb);
>  #define MUSB_QUIRK_B_INVALID_VBUS_91	(MUSB_DEVCTL_BDEVICE | \
>  					 (2 << MUSB_DEVCTL_VBUS_SHIFT) | \
>  					 MUSB_DEVCTL_SESSION)
> +#define MUSB_QUIRK_B_DISCONNECT_99	(MUSB_DEVCTL_BDEVICE | \
> +					 (3 << MUSB_DEVCTL_VBUS_SHIFT) | \
> +					 MUSB_DEVCTL_SESSION)
>  #define MUSB_QUIRK_A_DISCONNECT_19	((3 << MUSB_DEVCTL_VBUS_SHIFT) | \
>  					 MUSB_DEVCTL_SESSION)
>  
> @@ -1965,6 +1968,11 @@ static void musb_pm_runtime_check_session(struct musb *musb)
>  	s = MUSB_DEVCTL_FSDEV | MUSB_DEVCTL_LSDEV |
>  		MUSB_DEVCTL_HR;
>  	switch (devctl & ~s) {
> +	case MUSB_QUIRK_B_DISCONNECT_99:
> +		musb_dbg(musb, "Poll devctl in case of suspend after disconnect\n");
> +		schedule_delayed_work(&musb->irq_work,
> +				      msecs_to_jiffies(1000));
> +		break;
>  	case MUSB_QUIRK_B_INVALID_VBUS_91:
>  		if (musb->quirk_retries && !musb->flush_irq_work) {
>  			musb_dbg(musb,
> -- 
> 2.24.0