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Date:   Thu, 17 Jun 2021 15:22:30 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Linyu Yuan <linyyuan@codeaurora.org>
Cc:     Felipe Balbi <balbi@kernel.org>, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org, Linyu Yuan <linyyuan@codeaurora.com>
Subject: Re: [PATCH v3] usb: gadget: eem: fix echo command packet response
 issue
Message-ID: <YMtMlmwuIU3YmwAq@kroah.com>
References: <20210616115142.34075-1-linyyuan@codeaurora.org>
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On Wed, Jun 16, 2021 at 07:51:42PM +0800, Linyu Yuan wrote:
> From: Linyu Yuan <linyyuan@codeaurora.com>
> 
> when receive eem echo command, it will send a response,
> but queue this response to the usb request which allocate
> from gadget device endpoint zero,
> and transmit the request to IN endpoint of eem interface.
> 
> on dwc3 gadget, it will trigger following warning in function
> __dwc3_gadget_ep_queue(),
> 
> 	if (WARN(req->dep != dep, "request %pK belongs to '%s'\n",
> 				&req->request, req->dep->name))
> 		return -EINVAL;

Is this really a problem?  I am guessing the request will not work at
all?  Or just warn and continue with it?

How was this ever working?

> 
> fix it by allocating a usb request from IN endpoint of eem interface,
> and transmit the usb request to same IN endpoint of eem interface.
> 
> Signed-off-by: Linyu Yuan <linyyuan@codeaurora.com>
> ---

What commit does this fix?  Should it be backported to older stable
kernels?  If so, how far back?

thanks,

greg k-h