Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751573AbbLUP4I (ORCPT ); Mon, 21 Dec 2015 10:56:08 -0500 Received: from netrider.rowland.org ([192.131.102.5]:54748 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751401AbbLUP4F (ORCPT ); Mon, 21 Dec 2015 10:56:05 -0500 Date: Mon, 21 Dec 2015 10:56:04 -0500 (EST) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: Vikas Bansal cc: oneukum@suse.de, , , , Subject: Re: [PATCH] Adding Reset resume support for CDC-EEM driver. In-Reply-To: <1450699731-4666-1-git-send-email-vikas.bansal@samsung.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1374 Lines: 25 On Mon, 21 Dec 2015, Vikas Bansal wrote: > Pre-Condition > At the time of reset resume of a USB device, both self and bus powered devices might go to a low power state or power off state depending on the acceptable suspend time power of the system. > In case the device experiences a power glitch or completely powers off during suspend-resume, the device will lose its internal state and hence it'll again need a set interface from class driver on reset resume operation. > > Issue > So far our experiments were based on a USB gadget working on cdc_eem protocol. > We have seen that device is unable to continue the packet transfer on bulk endpoints after the reset resume operation. > > Solution > We have added a .reset_resume function for cdc_eem protocol which sends a set interface command on the Control endpoint. And calls the existing usbnet_resume thereafter You know, the USB core already issues a Set-Interface request on the control endpoint whenever a reset-resume occurs (unless the interface was using altsetting 0 beforehand). Issuing another Set-Interface shouldn't make any difference. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/