Re: [PATCH] usb: dwc3: gadget: skip Set/Clear Halt when invalid

[Felipe Balbi <felipe.balbi@linux.intel.com>]

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Hi John,

Felipe Balbi <felipe.balbi@linux.intel.com> writes:
> At least macOS seems to be sending
> ClearFeature(ENDPOINT_HALT) to endpoints which
> aren't Halted. This makes DWC3's CLEARSTALL command
> time out which causes several issues for the driver.
>
> Instead, let's just return 0 and bail out early.
>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
> ---
>
> this falls into "has never worked before" category, so I'll be sending
> it together with other patches for v4.11 merge window. Still, it's a
> valid bug that's likely needed for stable trees.
>
>  drivers/usb/dwc3/gadget.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 6faf484e5dfc..0a664d8eba3f 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1379,6 +1379,9 @@ int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value, int protocol)
>  		unsigned transfer_in_flight;
>  		unsigned started;
>  
> +		if (dep->flags & DWC3_EP_STALL)
> +			return 0;
> +
>  		if (dep->number > 1)
>  			trb = dwc3_ep_prev_trb(dep, dep->trb_enqueue);
>  		else
> @@ -1400,6 +1403,8 @@ int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value, int protocol)
>  		else
>  			dep->flags |= DWC3_EP_STALL;
>  	} else {
> +		if (!(dep->flags & DWC3_EP_STALL))
> +			return 0;
>  
>  		ret = dwc3_send_clear_stall_ep_cmd(dep);
>  		if (ret)

Reviving this old thread here. While $subject allowed dwc3 to work when
attached to macOS Host, I fear that we might have more issues than not
in the future. The reason is that USB20 spec allows hosts to use
ClearFeature(ENDPOINT_HALT) as a "Reset Data Toggle/SeqN" hint.

With this, we're basically blocking that possibility. Still, without
$subject, ClearStall commands were timing out. I'll try to do a local
revert here and check what happens in this case, but would you have any
idea why ClearStall would time out like that?

-- 
balbi

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